Read access violation when attempting strcpy from file buffer to char array
-1
I've been working on an assignment to implement hashing. In it, I read through a text file called "proteins". The problem occurs when I try to copy it to another char array. Visual Studio throws a read access violation.
#include <iostream>
#include <fstream>
using namespace std;
struct arrayelement
char protein[30];
int count;
;
arrayelement proteins[40];
int main()
char buffer[30];
// open source file
ifstream fin("proteins.txt");
if (!fin) cerr << "Input file could not be openedn"; exit(1);
// loop through strings in file
while (fin >> buffer)
int index = ((buffer[0] - 65) + (2 * (buffer[strlen(buffer)-1] - 65)) % 40);
while (true)
if (proteins[index].protein == buffer) // Found
proteins[index].count++;
break;
if (proteins[index].protein[0] == 0) // Empty
strcpy(proteins[index].protein, buffer); // <-- The error in question
proteins[index].count++;
break;
index++; // Collision
// close file
fin.close();
for (int i = 0; i <= 40; i++)
cout << proteins[i].protein << "t" << proteins[i].count << "n";
c++ arrays file char strcpy
asked Nov 13 '18 at 13:39
NoctimorNoctimor
31
add a comment |
-1
I've been working on an assignment to implement hashing. In it, I read through a text file called "proteins". The problem occurs when I try to copy it to another char array. Visual Studio throws a read access violation.
#include <iostream>
#include <fstream>
using namespace std;
struct arrayelement
char protein[30];
int count;
;
arrayelement proteins[40];
int main()
char buffer[30];
// open source file
ifstream fin("proteins.txt");
if (!fin) cerr << "Input file could not be openedn"; exit(1);
// loop through strings in file
while (fin >> buffer)
int index = ((buffer[0] - 65) + (2 * (buffer[strlen(buffer)-1] - 65)) % 40);
while (true)
if (proteins[index].protein == buffer) // Found
proteins[index].count++;
break;
if (proteins[index].protein[0] == 0) // Empty
strcpy(proteins[index].protein, buffer); // <-- The error in question
proteins[index].count++;
break;
index++; // Collision
// close file
fin.close();
for (int i = 0; i <= 40; i++)
cout << proteins[i].protein << "t" << proteins[i].count << "n";
c++ arrays file char strcpy
asked Nov 13 '18 at 13:39
NoctimorNoctimor
31
Did you try debug this? index may be at 40 when the error occurs.
– Matthieu Brucher
Nov 13 '18 at 13:40
Also usestd::stringand astd::vector<arrayelement>.
– Matthieu Brucher
Nov 13 '18 at 13:40
2
proteins[index].protein == bufferThis is not how you want to compare char arrays.
– 0x5453
Nov 13 '18 at 13:44
@0x5453 Oh man, I'm too tired. That did it. After changing that to a strcmp it all runs. Thank you!
– Noctimor
Nov 13 '18 at 13:50
@Noctimor Because you are trying to do C when you are in C++. Use containers....
– Matthieu Brucher
Nov 13 '18 at 13:51
add a comment |
-1
-1
-1
I've been working on an assignment to implement hashing. In it, I read through a text file called "proteins". The problem occurs when I try to copy it to another char array. Visual Studio throws a read access violation.
#include <iostream>
#include <fstream>
using namespace std;
struct arrayelement
char protein[30];
int count;
;
arrayelement proteins[40];
int main()
char buffer[30];
// open source file
ifstream fin("proteins.txt");
if (!fin) cerr << "Input file could not be openedn"; exit(1);
// loop through strings in file
while (fin >> buffer)
int index = ((buffer[0] - 65) + (2 * (buffer[strlen(buffer)-1] - 65)) % 40);
while (true)
if (proteins[index].protein == buffer) // Found
proteins[index].count++;
break;
if (proteins[index].protein[0] == 0) // Empty
strcpy(proteins[index].protein, buffer); // <-- The error in question
proteins[index].count++;
break;
index++; // Collision
// close file
fin.close();
for (int i = 0; i <= 40; i++)
cout << proteins[i].protein << "t" << proteins[i].count << "n";
c++ arrays file char strcpy
asked Nov 13 '18 at 13:39
NoctimorNoctimor
31
I've been working on an assignment to implement hashing. In it, I read through a text file called "proteins". The problem occurs when I try to copy it to another char array. Visual Studio throws a read access violation.
#include <iostream>
#include <fstream>
using namespace std;
struct arrayelement
char protein[30];
int count;
;
arrayelement proteins[40];
int main()
char buffer[30];
// open source file
ifstream fin("proteins.txt");
if (!fin) cerr << "Input file could not be openedn"; exit(1);
// loop through strings in file
while (fin >> buffer)
int index = ((buffer[0] - 65) + (2 * (buffer[strlen(buffer)-1] - 65)) % 40);
while (true)
if (proteins[index].protein == buffer) // Found
proteins[index].count++;
break;
if (proteins[index].protein[0] == 0) // Empty
strcpy(proteins[index].protein, buffer); // <-- The error in question
proteins[index].count++;
break;
index++; // Collision
// close file
fin.close();
for (int i = 0; i <= 40; i++)
cout << proteins[i].protein << "t" << proteins[i].count << "n";
c++ arrays file char strcpy
c++ arrays file char strcpy
asked Nov 13 '18 at 13:39
NoctimorNoctimor
31
asked Nov 13 '18 at 13:39
NoctimorNoctimor
31
asked Nov 13 '18 at 13:39
NoctimorNoctimor
31
asked Nov 13 '18 at 13:39
NoctimorNoctimor
31
asked Nov 13 '18 at 13:39
NoctimorNoctimor
31
31
Did you try debug this? index may be at 40 when the error occurs.
– Matthieu Brucher
Nov 13 '18 at 13:40
Also usestd::stringand astd::vector<arrayelement>.
– Matthieu Brucher
Nov 13 '18 at 13:40
2
proteins[index].protein == bufferThis is not how you want to compare char arrays.
– 0x5453
Nov 13 '18 at 13:44
@0x5453 Oh man, I'm too tired. That did it. After changing that to a strcmp it all runs. Thank you!
– Noctimor
Nov 13 '18 at 13:50
@Noctimor Because you are trying to do C when you are in C++. Use containers....
– Matthieu Brucher
Nov 13 '18 at 13:51
add a comment |
Did you try debug this? index may be at 40 when the error occurs.
– Matthieu Brucher
Nov 13 '18 at 13:40
Also usestd::stringand astd::vector<arrayelement>.
– Matthieu Brucher
Nov 13 '18 at 13:40
2
proteins[index].protein == bufferThis is not how you want to compare char arrays.
– 0x5453
Nov 13 '18 at 13:44
@0x5453 Oh man, I'm too tired. That did it. After changing that to a strcmp it all runs. Thank you!
– Noctimor
Nov 13 '18 at 13:50
@Noctimor Because you are trying to do C when you are in C++. Use containers....
– Matthieu Brucher
Nov 13 '18 at 13:51
Did you try debug this? index may be at 40 when the error occurs.
– Matthieu Brucher
Nov 13 '18 at 13:40
Did you try debug this? index may be at 40 when the error occurs.
– Matthieu Brucher
Nov 13 '18 at 13:40
Also use
std::string and a std::vector<arrayelement>.– Matthieu Brucher
Nov 13 '18 at 13:40
Also use
std::string and a std::vector<arrayelement>.– Matthieu Brucher
Nov 13 '18 at 13:40
2
2
proteins[index].protein == buffer This is not how you want to compare char arrays.– 0x5453
Nov 13 '18 at 13:44
proteins[index].protein == buffer This is not how you want to compare char arrays.– 0x5453
Nov 13 '18 at 13:44
@0x5453 Oh man, I'm too tired. That did it. After changing that to a strcmp it all runs. Thank you!
– Noctimor
Nov 13 '18 at 13:50
@0x5453 Oh man, I'm too tired. That did it. After changing that to a strcmp it all runs. Thank you!
– Noctimor
Nov 13 '18 at 13:50
@Noctimor Because you are trying to do C when you are in C++. Use containers....
– Matthieu Brucher
Nov 13 '18 at 13:51
@Noctimor Because you are trying to do C when you are in C++. Use containers....
– Matthieu Brucher
Nov 13 '18 at 13:51
add a comment |
1 Answer
1
active
oldest
votes
2
If you get more than 30 chars here:
while (fin >> buffer) {
... or if index >= 40 here:
strcpy(proteins[index].protein, buffer);
... the program will probably crash (Undefined behavior). Also, these char*'s will not be pointing at the same address, so the comparison will fail:
proteins[index].protein == buffer
answered Nov 13 '18 at 13:47
Ted LyngmoTed Lyngmo
2,8112317
Yep, it was the comparison that did me in. After rewriting it, everything runs. Part of the code here is given per the assignment -- the examples we're working with are guaranteed not to be above 30, and the index given is double what's needed, to practice collision resolution. Otherwise I'd absolutely clean that stuff up too. Thanks!
– Noctimor
Nov 13 '18 at 13:53
Great! Note: The index formula will result in 91 if the input string is"z". It'll become:index = 57 + 114 % 40=>57 + (114 % 40)
– Ted Lyngmo
Nov 13 '18 at 14:10
add a comment |
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2
If you get more than 30 chars here:
while (fin >> buffer) {
... or if index >= 40 here:
strcpy(proteins[index].protein, buffer);
... the program will probably crash (Undefined behavior). Also, these char*'s will not be pointing at the same address, so the comparison will fail:
proteins[index].protein == buffer
answered Nov 13 '18 at 13:47
Ted LyngmoTed Lyngmo
2,8112317
Yep, it was the comparison that did me in. After rewriting it, everything runs. Part of the code here is given per the assignment -- the examples we're working with are guaranteed not to be above 30, and the index given is double what's needed, to practice collision resolution. Otherwise I'd absolutely clean that stuff up too. Thanks!
– Noctimor
Nov 13 '18 at 13:53
Great! Note: The index formula will result in 91 if the input string is"z". It'll become:index = 57 + 114 % 40=>57 + (114 % 40)
– Ted Lyngmo
Nov 13 '18 at 14:10
add a comment |
2
If you get more than 30 chars here:
while (fin >> buffer) {
... or if index >= 40 here:
strcpy(proteins[index].protein, buffer);
... the program will probably crash (Undefined behavior). Also, these char*'s will not be pointing at the same address, so the comparison will fail:
proteins[index].protein == buffer
answered Nov 13 '18 at 13:47
Ted LyngmoTed Lyngmo
2,8112317
Yep, it was the comparison that did me in. After rewriting it, everything runs. Part of the code here is given per the assignment -- the examples we're working with are guaranteed not to be above 30, and the index given is double what's needed, to practice collision resolution. Otherwise I'd absolutely clean that stuff up too. Thanks!
– Noctimor
Nov 13 '18 at 13:53
Great! Note: The index formula will result in 91 if the input string is"z". It'll become:index = 57 + 114 % 40=>57 + (114 % 40)
– Ted Lyngmo
Nov 13 '18 at 14:10
add a comment |
2
2
2
If you get more than 30 chars here:
while (fin >> buffer) {
... or if index >= 40 here:
strcpy(proteins[index].protein, buffer);
... the program will probably crash (Undefined behavior). Also, these char*'s will not be pointing at the same address, so the comparison will fail:
proteins[index].protein == buffer
answered Nov 13 '18 at 13:47
Ted LyngmoTed Lyngmo
2,8112317
If you get more than 30 chars here:
while (fin >> buffer) {
... or if index >= 40 here:
strcpy(proteins[index].protein, buffer);
... the program will probably crash (Undefined behavior). Also, these char*'s will not be pointing at the same address, so the comparison will fail:
proteins[index].protein == buffer
answered Nov 13 '18 at 13:47
Ted LyngmoTed Lyngmo
2,8112317
answered Nov 13 '18 at 13:47
Ted LyngmoTed Lyngmo
2,8112317
answered Nov 13 '18 at 13:47
Ted LyngmoTed Lyngmo
2,8112317
answered Nov 13 '18 at 13:47
Ted LyngmoTed Lyngmo
2,8112317
2,8112317
Yep, it was the comparison that did me in. After rewriting it, everything runs. Part of the code here is given per the assignment -- the examples we're working with are guaranteed not to be above 30, and the index given is double what's needed, to practice collision resolution. Otherwise I'd absolutely clean that stuff up too. Thanks!
– Noctimor
Nov 13 '18 at 13:53
Great! Note: The index formula will result in 91 if the input string is"z". It'll become:index = 57 + 114 % 40=>57 + (114 % 40)
– Ted Lyngmo
Nov 13 '18 at 14:10
add a comment |
Yep, it was the comparison that did me in. After rewriting it, everything runs. Part of the code here is given per the assignment -- the examples we're working with are guaranteed not to be above 30, and the index given is double what's needed, to practice collision resolution. Otherwise I'd absolutely clean that stuff up too. Thanks!
– Noctimor
Nov 13 '18 at 13:53
Great! Note: The index formula will result in 91 if the input string is"z". It'll become:index = 57 + 114 % 40=>57 + (114 % 40)
– Ted Lyngmo
Nov 13 '18 at 14:10
Yep, it was the comparison that did me in. After rewriting it, everything runs. Part of the code here is given per the assignment -- the examples we're working with are guaranteed not to be above 30, and the index given is double what's needed, to practice collision resolution. Otherwise I'd absolutely clean that stuff up too. Thanks!
– Noctimor
Nov 13 '18 at 13:53
Yep, it was the comparison that did me in. After rewriting it, everything runs. Part of the code here is given per the assignment -- the examples we're working with are guaranteed not to be above 30, and the index given is double what's needed, to practice collision resolution. Otherwise I'd absolutely clean that stuff up too. Thanks!
– Noctimor
Nov 13 '18 at 13:53
Great! Note: The index formula will result in 91 if the input string is
"z". It'll become: index = 57 + 114 % 40 => 57 + (114 % 40)– Ted Lyngmo
Nov 13 '18 at 14:10
Great! Note: The index formula will result in 91 if the input string is
"z". It'll become: index = 57 + 114 % 40 => 57 + (114 % 40)– Ted Lyngmo
Nov 13 '18 at 14:10
add a comment |
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Did you try debug this? index may be at 40 when the error occurs.
– Matthieu Brucher
Nov 13 '18 at 13:40
Also use
std::stringand astd::vector<arrayelement>.– Matthieu Brucher
Nov 13 '18 at 13:40
2
proteins[index].protein == bufferThis is not how you want to compare char arrays.– 0x5453
Nov 13 '18 at 13:44
@0x5453 Oh man, I'm too tired. That did it. After changing that to a strcmp it all runs. Thank you!
– Noctimor
Nov 13 '18 at 13:50
@Noctimor Because you are trying to do C when you are in C++. Use containers....
– Matthieu Brucher
Nov 13 '18 at 13:51