How do I trim leading/trailing whitespace in a standard way?

Question

Is there a clean, preferably standard method of trimming leading and trailing whitespace from a string in C? I\'d roll my own, but I would think this is a common problem wit

Answer 1

This one is short and simple, uses for-loops and doesn't overwrite the string boundaries. You can replace the test with isspace() if needed.

void trim (char *s)         // trim leading and trailing spaces+tabs
{
 int i,j,k, len;

 j=k=0;
 len = strlen(s);
                    // find start of string
 for (i=0; i=j; i--) if ((s[i]!=32) && (s[i]!=9)) { k=i+1; break;} 

 if (k<=j) {s[0]=0; return;}        // all whitespace (j==k==0)

 len=k-j;
 for (i=0; i