CODEWITHSUNDEEP
cstringfile
codedude
codedude

Reputation: 6549

Find string in text file in C

I'm trying to search a text file using C for a string of characters that will always be in a specific place. Specifically I'm looking for three sequential dashes. When it finds the three dashes it should return the line on which it was found. It should then continue to the next line and continue searching for the three sequential dashes until it reaches the end of the file. Each time is should print the line number.

This is what I have so far:

int main() {
FILE *f;
char inName[80];
printf("Read text from: ");
scanf(" %79[^\n]s\n", inName);

f  = fopen(inName, "r");
if (f == 0) printf("ERROR: Cannot open file %s for reading.\n", inName);
int lineNumber = 0;

for(;;) {       
    char line[127]; 
    fgets(line, 127, f);
    if (!feof(f)) { 
        lineNumber++;
    } else {
        break;
    }

    double lf;  
    int d, d1;
    char s[30];
    char s1[4];

    sscanf(line, " %d, %s, %s, %s, %s, %d, %d, %lf",
                   &d, &s, &s, &s, &s, &d, &s1, &lf);
    if (s1 == "---") {
        printf("%d\n", lineNumber); // what line 
    }
}
fclose(f);

return(0);
}

This code runs but does not print anything. Could anyone show how to get this done? Thanks :)

Upvotes: 1

Views: 13181

Answers (3)

hmjd
hmjd

Reputation: 122011

This is not how to compare strings in C:

if (s1 == "---")

as is comparing the address of s1 with the address of the string literal "---". Use strcmp():

if (strcmp(s1, "---") == 0)
{

Always check the return value of sscanf() to ensure the variables have actually been assigned a value before attempting to use them. The , comma character is not treated as delimiter when processed with "%s" format specifier, only whitespace is used as delimiter. To prevent the consumption of the , use a scan set, similar to how you have done earlier in the program (note corrections to sscanf() arguments):

if (sscanf(line,
           " %d, %29[^,], %29[^,], %29[^,], %29[^,], %d, %3[^,], %lf",
             &d, s,       s,       s,       s,       &d, s1,     &lf) == 8)
{
}

Upvotes: 5

Kara
Kara

Reputation: 6226

You cannot compare char[] with ==. Use strcmp instead.

if( strcmp(s1, "---") == 0 )

Upvotes: 2

Tim
Tim

Reputation: 43364

if (s1 == "---")

You're comparing strings the wrong way, you should use strcmp()

follow this example http://faq.cprogramming.com/cgi-bin/smartfaq.cgi?answer=1057537653&id=1043284385

Upvotes: 5

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