Extract integer from char buffer

Hi

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

From stackoverflow

• 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.

  Makis : You still have to parse the string because doesn't atoi() return 0 if your string starts with a non-numerical value?

  Adrian Panasiuk : `strtol` is better than `atoi` as it allows you to handle errors.

• Can use sscanf per line, like:

  #include <stdio.h>
  int time;
  char* str = "Timings results : 120012";
  
  int n = sscanf(str, "Timings results : %d", &time);
  

  in this case n == 1 means success