strstr error

[mtbrooks1993]

I'm using strstr to search a c-string but it doesn't return false. The compiler just crashes when it checks for the value. What can I do to fix this?

#include<iostream>
#include<cctype>
#include<cstring>
#include<fstream>
using namespace std;

void read();
void ignoreRead(char []);
void writeOver(char [], char [], char []);
void otherway();
bool search(char [], char []);

int main()
{
	//char word1[20], sub1[20];

	read();

	return 0;
}

void read()
{
	char word1[20];
	char sub1[20];
	char sentence[1000];
	char no[] = "$";
	ifstream infile;
	infile.open("paragraphwordssub.txt");
	ignoreRead(sentence);

	infile >> word1;
	cout << word1 << endl;
	infile >> sub1;
	cout << sub1 << endl;

	while (word1[0] != no[0])
	{

		writeOver(word1, sub1, sentence);
		cout << sentence << endl;
		infile >> word1;
		cout << word1 << endl;
		infile >> sub1;
		cout << sub1 << endl;

	}

	infile.close();
}

void ignoreRead(char sentence2[1000])
{
	ifstream infile;
	infile.open("paragraphwordssub.txt");
	char word = '$';
	char ignore[20];
	char sentence1[1000];
	//char sentence2[1000];
	infile >> ignore;

	while (ignore[0] != word)
	{
		infile >> ignore;
	}
	infile.getline(ignore, 100);

	infile.getline(sentence1, 1000);
	infile.getline(sentence2, 1000);
	//cout << sentence1 << endl;;
	//cout << sentence2 << endl;
}

void writeOver(char word1[20], char sub1[20], char sentence[1000])
{
	char *sptr;
	char temp[1000]="";
	int len1, len2, len3;
	bool found = true;
	sptr = strstr(sentence, word1);
	//cout << sptr << endl;
	while (found)
	{
		len1 = strlen(sentence);
		len2 = strlen(sptr);
		len3 = len1 - len2;

		strncpy(temp, sentence, len3);
		strcat(temp, sub1);
		strcat(temp, sptr + strlen(word1));

		for (int x = 0; x < 1000; x++)
		{
			sentence[x] = temp[x];
		}

		found = search(word1, sentence);
		sptr = strstr(sentence, word1);
		
	}
	//cout << sentence << endl;
}

bool search(char word1[20], char sentence[1000])
{
	char *sptr = NULL;
	sptr = strstr(sentence, word1);
	//cout << sptr << endl;
	if (sptr == NULL) ///this is where the compiler crashes
	{
		return false;
	}
	else
	{
		return true;
	}
}

[coder777]

I'd guess that the problem occurs on line 85. What happens if line 80 return NULL?

[mtbrooks1993]

I added a check for found on line 81 so it won't enter the loop if it returns NULL, but it still crashes out?

#include<iostream>
#include<cctype>
#include<cstring>
#include<fstream>
using namespace std;

void read();
void ignoreRead(char []);
void writeOver(char [], char [], char []);
void otherway();
bool search(char [], char []);

int main()
{
	//char word1[20], sub1[20];

	read();

	return 0;
}

void read()
{
	char word1[20];
	char sub1[20];
	char sentence[1000];
	char no[] = "$";
	ifstream infile;
	infile.open("paragraphwordssub.txt");
	ignoreRead(sentence);

	infile >> word1;
	cout << word1 << endl;
	infile >> sub1;
	cout << sub1 << endl;

	while (word1[0] != no[0])
	{

		writeOver(word1, sub1, sentence);
		cout << sentence << endl;
		infile >> word1;
		cout << word1 << endl;
		infile >> sub1;
		cout << sub1 << endl;

	}

	infile.close();
}

void ignoreRead(char sentence2[1000])
{
	ifstream infile;
	infile.open("paragraphwordssub.txt");
	char word = '$';
	char ignore[20];
	char sentence1[1000];
	//char sentence2[1000];
	infile >> ignore;

	while (ignore[0] != word)
	{
		infile >> ignore;
	}
	infile.getline(ignore, 100);

	infile.getline(sentence1, 1000);
	infile.getline(sentence2, 1000);
	//cout << sentence1 << endl;;
	//cout << sentence2 << endl;
}

void writeOver(char word1[20], char sub1[20], char sentence[1000])
{
	char *sptr;
	char temp[1000]="";
	int len1, len2, len3;
	bool found = true;
	sptr = strstr(sentence, word1);
	//cout << sptr << endl;
	found = search(word1, sentence); //added this
	while (found)
	{
		len1 = strlen(sentence);
		len2 = strlen(sptr);
		len3 = len1 - len2;

		strncpy(temp, sentence, len3);
		strcat(temp, sub1);
		strcat(temp, sptr + strlen(word1));

		for (int x = 0; x < 1000; x++)
		{
			sentence[x] = temp[x];
		}

		found = search(word1, sentence);
		sptr = strstr(sentence, word1);
		
	}
	//cout << sentence << endl;
}

bool search(char word1[20], char sentence[1000])
{
	char *sptr = NULL;
	sptr = strstr(sentence, word1);
	//cout << sptr << endl;
	if (sptr == NULL) ///this is where the compiler crashes
	{
		return false;
	}
	else
	{
		return true;
	}
}

[jlb]

please post a small sample of your input file.

Also why are you using the C-strings instead of the C++ string?


Edit: And a little documentation as to what each function is trying to accomplish would be wonderful.

[mtbrooks1993]

The read function reads in a word then a word that it wants to sub it with.

The ignoreRead function reads in the paragraph that I'm swapping words in it skips the words I swap.

The search function looks to see if the word I want to swap is in the paragraph.

The writeover function swaps the words.

Input file looks like this but is different words but I want it to work for any file that has this format:
{
word word1
wahy wodue
adlfj idejrd

$

word the wahy a word apple wahy tin adlfj this word wahy
}

I want to swap the first word for the second word for every time the word occurs

I am using c-strings because I have already written this in strings and I am trying to do it the old way.

If I run it without the while(found) loop in the writeover function it only replaces the first word even if the word is in there multiple times