Question

char testStr[] = "          trim this           ";
char** pTestStr = &testStr;
trim(pTestStr);

int trim(char** pStr)
{
 char* str = *pStr;
 while(isspace(*str)) {
  (*pStr)++;
  str++;
 }

 if(*str == 0) {
  return 0;
 }

 char *end = str + strlen(str) - 1;
 while(end > str && isspace(*end))
  end--;
 *(end+1) = 0;

 return 0;
}

Answer 1

char testStr[] = "          trim this           ";
char* pTestStr = &testStr[0];
trim(&pTestStr);

void trim(char* str)
{
    if(!str)
        return;

    char* ptr = str;
    int len = strlen(ptr);

    while(len-1 > 0 && isspace(ptr[len-1]))
        ptr[--len] = 0;

    while(*ptr && isspace(*ptr))
        ++ptr, --len;

    memmove(str, ptr, len + 1);
}