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

#include 
#include 

char *trim_space(char *in)
{
    char *out = NULL;
    int len;
    if (in) {
        len = strlen(in);
        while(len && isspace(in[len - 1])) --len;
        while(len && *in && isspace(*in)) ++in, --len;
        if (len) {
            out = strndup(in, len);
        }
    }
    return out;
}

isspace helps to trim all white spaces.

• Run a first loop to check from last byte for space character and reduce the length variable
• Run a second loop to check from first byte for space character and reduce the length variable and increment char pointer.
• Finally if length variable is more than 0, then use strndup to create new string buffer by excluding spaces.