I have a very simple problem in C. I am reading a file linewise, and store it in a buffer
char line[80];
Each line has the following structure:
Timings results : 2215543
Timings results : 22155431
Timings results : 221554332
Timings results : 2215543
What I am trying to do, is to extract the integer value from this line. Does C here provide any simple function that allows me to do that?
Thanks
Can use sscanf per line, like:
#include <stdio.h>
int time = -1;
char* str = "Timings results : 120012";
int n = sscanf(str, "Timings results : %d", &time);
in this case n == 1 means success
Yes - try atoi
int n=atoi(str);
In your example, you have a fixed prefix before the integer, so you could simply add an offset to szLine before passing it to atoi, e.g.
int offset=strlen("Timings results : ");
int timing=atoi(szLine + offset);
Pretty efficient, but doesn't cope well with lines which aren't as expected. You could check each line first though:
const char * prefix="Timings results : ";
int offset=strlen(prefix);
char * start=strstr(szLine, prefix);
if (start)
{
int timing=atoi(start+offset);
//do whatever you need to do
}
else
{
//line didn't match
}
You can also use sscanf for parsing lines like this, which makes for more concise code:
int timing;
sscanf(szLine, "Timings results : %d", &timing);
Finally, see also Parsing Integer to String C for further ideas.
strtol is better than atoi as it allows you to handle errors.