Why does cout fail to output strings sometimes, but printf has no problem?
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Problem: when printing items in a hash table, non top-level items do not print correctly.
I add items line-by-line from a text file. First, number of lines are determined, and then, the hash table is constructed, with the size found in the first loop of the file.
hash constructor
hash::hash(unsigned int tSize)
{
this->tableSize = tSize;
hashTable.resize(tableSize);
for (int i = 0; i < tableSize; i++)
{
hashTable[i] = new item;
hashTable[i]->firstLetters = "__";
hashTable[i]->str = "____";
hashTable[i]->next = NULL;
}
}
adding items, setting values, and printing them
void hash::add(std::string key)
{
int index = hafn(key);
if (hashTable[index]->str == "____")
{
hashTable[index]->str = key;
setFirstLetters(index,key[0],key[1]);
}
else
{
item *iter = hashTable[index];
item *n_ptr = new item;
n_ptr->str = key;
setFirstLetters(n_ptr, key[0], key[1]);
n_ptr->next = NULL;
while (iter->next != NULL)
{
iter = iter->next;
}
iter->next = n_ptr;
}
}
void hash::setFirstLetters(item *n_ptr, char a, char b)
{
n_ptr->firstLetters[0] = a;
n_ptr->firstLetters[1] = b;
}
void hash::setFirstLetters(int index, char a, char b)
{
hashTable[index]->firstLetters[0] = a;
hashTable[index]->firstLetters[1] = b;
}
void hash::print()
{
int num;
for (int i = 0; i < tableSize; i++)
{
num = numInIndex(i);
printer(num, i);
if (num > 1)
{
int c = 0;
for (int j = num - 1; j > 0; j--)
{
printer(c, num, i);
c++;
}
}
}
}
void hash::printer(int num, int i)
{
item *iter = hashTable[i];
cout << "-------------------------------" << endl;
cout << "index = " << i << endl;
cout << iter->str << endl;
cout << iter->firstLetters << endl;
cout << "# of items = " << num << endl;
cout << "-------------------------------" << endl;
cout << endl;
}
void hash::printer(int numIn, int num, int i)
{
item *iter = hashTable[i];
for (int j = 0; j < numIn; j++)
{
iter = iter->next;
}
cout << "-------------------------------" << endl;
cout << "index = " << i << endl;
cout << iter->str << endl;
cout << std::flush;
cout << iter->firstLetters << endl; //this does not work, though the pointer is pointing to the correct values
//printf("%sn", iter->firstLetters.c_str()); //this works, even without flushing
cout << "# of items = " << num << endl;
cout << "-------------------------------" << endl;
cout << endl;
}
struct item
{
std::string str;
std::string firstLetters;
item *next;
};
The problem is that firstLetters does not print correctly. firstLetters is set correctly. However, in third- and later level items (ie, using the same hash index), firstLetters does not print at all.
In order to be more clear, here is an output example:
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
good
# of items = 3
-------------------------------
A correct example of output would be this:
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
good
go
# of items = 3
-------------------------------
c++ hash printf cout string-hashing
asked Nov 12 at 23:33
Adam
125
|
show 11 more comments
up vote
0
down vote
favorite
Problem: when printing items in a hash table, non top-level items do not print correctly.
I add items line-by-line from a text file. First, number of lines are determined, and then, the hash table is constructed, with the size found in the first loop of the file.
hash constructor
hash::hash(unsigned int tSize)
{
this->tableSize = tSize;
hashTable.resize(tableSize);
for (int i = 0; i < tableSize; i++)
{
hashTable[i] = new item;
hashTable[i]->firstLetters = "__";
hashTable[i]->str = "____";
hashTable[i]->next = NULL;
}
}
adding items, setting values, and printing them
void hash::add(std::string key)
{
int index = hafn(key);
if (hashTable[index]->str == "____")
{
hashTable[index]->str = key;
setFirstLetters(index,key[0],key[1]);
}
else
{
item *iter = hashTable[index];
item *n_ptr = new item;
n_ptr->str = key;
setFirstLetters(n_ptr, key[0], key[1]);
n_ptr->next = NULL;
while (iter->next != NULL)
{
iter = iter->next;
}
iter->next = n_ptr;
}
}
void hash::setFirstLetters(item *n_ptr, char a, char b)
{
n_ptr->firstLetters[0] = a;
n_ptr->firstLetters[1] = b;
}
void hash::setFirstLetters(int index, char a, char b)
{
hashTable[index]->firstLetters[0] = a;
hashTable[index]->firstLetters[1] = b;
}
void hash::print()
{
int num;
for (int i = 0; i < tableSize; i++)
{
num = numInIndex(i);
printer(num, i);
if (num > 1)
{
int c = 0;
for (int j = num - 1; j > 0; j--)
{
printer(c, num, i);
c++;
}
}
}
}
void hash::printer(int num, int i)
{
item *iter = hashTable[i];
cout << "-------------------------------" << endl;
cout << "index = " << i << endl;
cout << iter->str << endl;
cout << iter->firstLetters << endl;
cout << "# of items = " << num << endl;
cout << "-------------------------------" << endl;
cout << endl;
}
void hash::printer(int numIn, int num, int i)
{
item *iter = hashTable[i];
for (int j = 0; j < numIn; j++)
{
iter = iter->next;
}
cout << "-------------------------------" << endl;
cout << "index = " << i << endl;
cout << iter->str << endl;
cout << std::flush;
cout << iter->firstLetters << endl; //this does not work, though the pointer is pointing to the correct values
//printf("%sn", iter->firstLetters.c_str()); //this works, even without flushing
cout << "# of items = " << num << endl;
cout << "-------------------------------" << endl;
cout << endl;
}
struct item
{
std::string str;
std::string firstLetters;
item *next;
};
The problem is that firstLetters does not print correctly. firstLetters is set correctly. However, in third- and later level items (ie, using the same hash index), firstLetters does not print at all.
In order to be more clear, here is an output example:
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
good
# of items = 3
-------------------------------
A correct example of output would be this:
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
good
go
# of items = 3
-------------------------------
c++ hash printf cout string-hashing
asked Nov 12 at 23:33
Adam
125
I have been using the debugger continually. On the line thatfirstLettersis printed, that variable is correct insidestruct item
– Adam
Nov 12 at 23:42
You seem to be expecting us to debug your uncompilable code.
– Neil Butterworth
Nov 12 at 23:44
I am not. The code does compile. I haven't given every single piece of code, only the relevant ones. I just need help on situations thatcoutwill not print, even though the output stream has been flushed.
– Adam
Nov 12 at 23:45
2
Bug in there somewhere that isn't jumping out at me. Could we trouble you for a Minimal, Complete, and Verifiable example? This is important because if you don't know what the bug is, how can you know what is and what isn't relevant? The real beauty of the MCVE is usually you get in part way and the reduced code to bug ratio reveals the bug to you.
– user4581301
Nov 12 at 23:46
1
@Adam You are initializingfirstLetters = "__"only for the initial top-levelitemobjects that thehashconstructor creates, but you are NOT initializingfirstLettersto anything in the secondaryitemobjects thathash::add()creates, son_ptr->firstLettersis blank whensetFirstLetters(n_ptr, ...)is called, sosetFirstLetters()tries to index into invalid memory. If you wantfirstLettersto alows be initialized as"__", you should add a constructor to theitem` struct for that.
– Remy Lebeau
Nov 13 at 0:14
|
show 11 more comments
up vote
0
down vote
favorite
up vote
0
down vote
favorite
Problem: when printing items in a hash table, non top-level items do not print correctly.
I add items line-by-line from a text file. First, number of lines are determined, and then, the hash table is constructed, with the size found in the first loop of the file.
hash constructor
hash::hash(unsigned int tSize)
{
this->tableSize = tSize;
hashTable.resize(tableSize);
for (int i = 0; i < tableSize; i++)
{
hashTable[i] = new item;
hashTable[i]->firstLetters = "__";
hashTable[i]->str = "____";
hashTable[i]->next = NULL;
}
}
adding items, setting values, and printing them
void hash::add(std::string key)
{
int index = hafn(key);
if (hashTable[index]->str == "____")
{
hashTable[index]->str = key;
setFirstLetters(index,key[0],key[1]);
}
else
{
item *iter = hashTable[index];
item *n_ptr = new item;
n_ptr->str = key;
setFirstLetters(n_ptr, key[0], key[1]);
n_ptr->next = NULL;
while (iter->next != NULL)
{
iter = iter->next;
}
iter->next = n_ptr;
}
}
void hash::setFirstLetters(item *n_ptr, char a, char b)
{
n_ptr->firstLetters[0] = a;
n_ptr->firstLetters[1] = b;
}
void hash::setFirstLetters(int index, char a, char b)
{
hashTable[index]->firstLetters[0] = a;
hashTable[index]->firstLetters[1] = b;
}
void hash::print()
{
int num;
for (int i = 0; i < tableSize; i++)
{
num = numInIndex(i);
printer(num, i);
if (num > 1)
{
int c = 0;
for (int j = num - 1; j > 0; j--)
{
printer(c, num, i);
c++;
}
}
}
}
void hash::printer(int num, int i)
{
item *iter = hashTable[i];
cout << "-------------------------------" << endl;
cout << "index = " << i << endl;
cout << iter->str << endl;
cout << iter->firstLetters << endl;
cout << "# of items = " << num << endl;
cout << "-------------------------------" << endl;
cout << endl;
}
void hash::printer(int numIn, int num, int i)
{
item *iter = hashTable[i];
for (int j = 0; j < numIn; j++)
{
iter = iter->next;
}
cout << "-------------------------------" << endl;
cout << "index = " << i << endl;
cout << iter->str << endl;
cout << std::flush;
cout << iter->firstLetters << endl; //this does not work, though the pointer is pointing to the correct values
//printf("%sn", iter->firstLetters.c_str()); //this works, even without flushing
cout << "# of items = " << num << endl;
cout << "-------------------------------" << endl;
cout << endl;
}
struct item
{
std::string str;
std::string firstLetters;
item *next;
};
The problem is that firstLetters does not print correctly. firstLetters is set correctly. However, in third- and later level items (ie, using the same hash index), firstLetters does not print at all.
In order to be more clear, here is an output example:
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
good
# of items = 3
-------------------------------
A correct example of output would be this:
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
good
go
# of items = 3
-------------------------------
c++ hash printf cout string-hashing
asked Nov 12 at 23:33
Adam
125
Problem: when printing items in a hash table, non top-level items do not print correctly.
I add items line-by-line from a text file. First, number of lines are determined, and then, the hash table is constructed, with the size found in the first loop of the file.
hash constructor
hash::hash(unsigned int tSize)
{
this->tableSize = tSize;
hashTable.resize(tableSize);
for (int i = 0; i < tableSize; i++)
{
hashTable[i] = new item;
hashTable[i]->firstLetters = "__";
hashTable[i]->str = "____";
hashTable[i]->next = NULL;
}
}
adding items, setting values, and printing them
void hash::add(std::string key)
{
int index = hafn(key);
if (hashTable[index]->str == "____")
{
hashTable[index]->str = key;
setFirstLetters(index,key[0],key[1]);
}
else
{
item *iter = hashTable[index];
item *n_ptr = new item;
n_ptr->str = key;
setFirstLetters(n_ptr, key[0], key[1]);
n_ptr->next = NULL;
while (iter->next != NULL)
{
iter = iter->next;
}
iter->next = n_ptr;
}
}
void hash::setFirstLetters(item *n_ptr, char a, char b)
{
n_ptr->firstLetters[0] = a;
n_ptr->firstLetters[1] = b;
}
void hash::setFirstLetters(int index, char a, char b)
{
hashTable[index]->firstLetters[0] = a;
hashTable[index]->firstLetters[1] = b;
}
void hash::print()
{
int num;
for (int i = 0; i < tableSize; i++)
{
num = numInIndex(i);
printer(num, i);
if (num > 1)
{
int c = 0;
for (int j = num - 1; j > 0; j--)
{
printer(c, num, i);
c++;
}
}
}
}
void hash::printer(int num, int i)
{
item *iter = hashTable[i];
cout << "-------------------------------" << endl;
cout << "index = " << i << endl;
cout << iter->str << endl;
cout << iter->firstLetters << endl;
cout << "# of items = " << num << endl;
cout << "-------------------------------" << endl;
cout << endl;
}
void hash::printer(int numIn, int num, int i)
{
item *iter = hashTable[i];
for (int j = 0; j < numIn; j++)
{
iter = iter->next;
}
cout << "-------------------------------" << endl;
cout << "index = " << i << endl;
cout << iter->str << endl;
cout << std::flush;
cout << iter->firstLetters << endl; //this does not work, though the pointer is pointing to the correct values
//printf("%sn", iter->firstLetters.c_str()); //this works, even without flushing
cout << "# of items = " << num << endl;
cout << "-------------------------------" << endl;
cout << endl;
}
struct item
{
std::string str;
std::string firstLetters;
item *next;
};
The problem is that firstLetters does not print correctly. firstLetters is set correctly. However, in third- and later level items (ie, using the same hash index), firstLetters does not print at all.
In order to be more clear, here is an output example:
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
good
# of items = 3
-------------------------------
A correct example of output would be this:
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
will
wi
# of items = 3
-------------------------------
-------------------------------
index = 15
good
go
# of items = 3
-------------------------------
c++ hash printf cout string-hashing
c++ hash printf cout string-hashing
asked Nov 12 at 23:33
Adam
125
asked Nov 12 at 23:33
Adam
125
edited Nov 13 at 0:28
asked Nov 12 at 23:33
Adam
125
asked Nov 12 at 23:33
Adam
125
asked Nov 12 at 23:33
Adam
125
125
I have been using the debugger continually. On the line thatfirstLettersis printed, that variable is correct insidestruct item
– Adam
Nov 12 at 23:42
You seem to be expecting us to debug your uncompilable code.
– Neil Butterworth
Nov 12 at 23:44
I am not. The code does compile. I haven't given every single piece of code, only the relevant ones. I just need help on situations thatcoutwill not print, even though the output stream has been flushed.
– Adam
Nov 12 at 23:45
2
Bug in there somewhere that isn't jumping out at me. Could we trouble you for a Minimal, Complete, and Verifiable example? This is important because if you don't know what the bug is, how can you know what is and what isn't relevant? The real beauty of the MCVE is usually you get in part way and the reduced code to bug ratio reveals the bug to you.
– user4581301
Nov 12 at 23:46
1
@Adam You are initializingfirstLetters = "__"only for the initial top-levelitemobjects that thehashconstructor creates, but you are NOT initializingfirstLettersto anything in the secondaryitemobjects thathash::add()creates, son_ptr->firstLettersis blank whensetFirstLetters(n_ptr, ...)is called, sosetFirstLetters()tries to index into invalid memory. If you wantfirstLettersto alows be initialized as"__", you should add a constructor to theitem` struct for that.
– Remy Lebeau
Nov 13 at 0:14
|
show 11 more comments
I have been using the debugger continually. On the line thatfirstLettersis printed, that variable is correct insidestruct item
– Adam
Nov 12 at 23:42
You seem to be expecting us to debug your uncompilable code.
– Neil Butterworth
Nov 12 at 23:44
I am not. The code does compile. I haven't given every single piece of code, only the relevant ones. I just need help on situations thatcoutwill not print, even though the output stream has been flushed.
– Adam
Nov 12 at 23:45
2
Bug in there somewhere that isn't jumping out at me. Could we trouble you for a Minimal, Complete, and Verifiable example? This is important because if you don't know what the bug is, how can you know what is and what isn't relevant? The real beauty of the MCVE is usually you get in part way and the reduced code to bug ratio reveals the bug to you.
– user4581301
Nov 12 at 23:46
1
@Adam You are initializingfirstLetters = "__"only for the initial top-levelitemobjects that thehashconstructor creates, but you are NOT initializingfirstLettersto anything in the secondaryitemobjects thathash::add()creates, son_ptr->firstLettersis blank whensetFirstLetters(n_ptr, ...)is called, sosetFirstLetters()tries to index into invalid memory. If you wantfirstLettersto alows be initialized as"__", you should add a constructor to theitem` struct for that.
– Remy Lebeau
Nov 13 at 0:14
I have been using the debugger continually. On the line that
firstLetters is printed, that variable is correct inside struct item– Adam
Nov 12 at 23:42
I have been using the debugger continually. On the line that
firstLetters is printed, that variable is correct inside struct item– Adam
Nov 12 at 23:42
You seem to be expecting us to debug your uncompilable code.
– Neil Butterworth
Nov 12 at 23:44
You seem to be expecting us to debug your uncompilable code.
– Neil Butterworth
Nov 12 at 23:44
I am not. The code does compile. I haven't given every single piece of code, only the relevant ones. I just need help on situations that
cout will not print, even though the output stream has been flushed.– Adam
Nov 12 at 23:45
I am not. The code does compile. I haven't given every single piece of code, only the relevant ones. I just need help on situations that
cout will not print, even though the output stream has been flushed.– Adam
Nov 12 at 23:45
2
2
Bug in there somewhere that isn't jumping out at me. Could we trouble you for a Minimal, Complete, and Verifiable example? This is important because if you don't know what the bug is, how can you know what is and what isn't relevant? The real beauty of the MCVE is usually you get in part way and the reduced code to bug ratio reveals the bug to you.
– user4581301
Nov 12 at 23:46
Bug in there somewhere that isn't jumping out at me. Could we trouble you for a Minimal, Complete, and Verifiable example? This is important because if you don't know what the bug is, how can you know what is and what isn't relevant? The real beauty of the MCVE is usually you get in part way and the reduced code to bug ratio reveals the bug to you.
– user4581301
Nov 12 at 23:46
1
1
@Adam You are initializing
firstLetters = "__" only for the initial top-level item objects that the hash constructor creates, but you are NOT initializing firstLetters to anything in the secondary item objects that hash::add() creates, so n_ptr->firstLetters is blank when setFirstLetters(n_ptr, ...) is called, so setFirstLetters() tries to index into invalid memory. If you want firstLetters to alows be initialized as "__", you should add a constructor to the item` struct for that.– Remy Lebeau
Nov 13 at 0:14
@Adam You are initializing
firstLetters = "__" only for the initial top-level item objects that the hash constructor creates, but you are NOT initializing firstLetters to anything in the secondary item objects that hash::add() creates, so n_ptr->firstLetters is blank when setFirstLetters(n_ptr, ...) is called, so setFirstLetters() tries to index into invalid memory. If you want firstLetters to alows be initialized as "__", you should add a constructor to the item` struct for that.– Remy Lebeau
Nov 13 at 0:14
|
show 11 more comments
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I have been using the debugger continually. On the line that
firstLettersis printed, that variable is correct insidestruct item– Adam
Nov 12 at 23:42
You seem to be expecting us to debug your uncompilable code.
– Neil Butterworth
Nov 12 at 23:44
I am not. The code does compile. I haven't given every single piece of code, only the relevant ones. I just need help on situations that
coutwill not print, even though the output stream has been flushed.– Adam
Nov 12 at 23:45
2
Bug in there somewhere that isn't jumping out at me. Could we trouble you for a Minimal, Complete, and Verifiable example? This is important because if you don't know what the bug is, how can you know what is and what isn't relevant? The real beauty of the MCVE is usually you get in part way and the reduced code to bug ratio reveals the bug to you.
– user4581301
Nov 12 at 23:46
1
@Adam You are initializing
firstLetters = "__"only for the initial top-levelitemobjects that thehashconstructor creates, but you are NOT initializingfirstLettersto anything in the secondaryitemobjects thathash::add()creates, son_ptr->firstLettersis blank whensetFirstLetters(n_ptr, ...)is called, sosetFirstLetters()tries to index into invalid memory. If you wantfirstLettersto alows be initialized as"__", you should add a constructor to theitem` struct for that.– Remy Lebeau
Nov 13 at 0:14