These points are mostly designed-oriented:

• I'd recommend having len() return a size_t while making i the same type. This type is preferred for size functions (especially library ones) because it is unsigned (non-negatives), whereas int is signed (non-negatives and negatives).

• Although just another form, lstrip() can be done this way:

    char* lstrip (char* string) {
  
        // skip and return right away if condition is not met
        if (string) {
        /* Trim off leading whitespace */
        while (*string == ' ') {
            string++;
        }
  
        return string;
    }
  

  Also, your plain return won't work because the function is supposed to return a char*.

These points are mostly designed-oriented:

• I'd recommend having len() return a size_t with i as the same type. This type is preferred for size functions and is also used in libraries.

• Although just another form, lstrip() can be done this way:

    char* lstrip (char* string) {
  
        // skip and return right away if condition is not met
        if (string) {
            /* Trim off leading whitespace */
            while (*string == ' ') {
                string++;
            }
        }
  
        return string;
    }
  

  Also, your plain return won't work because the function is supposed to return a char*.

These points are mostly designed-oriented:

• I'd recommend having len() return a size_t while also making i the same type. This is preferred for size functions (especially library ones) because it is unsigned (non-negatives), whereas int is signed (negatives).

• Although just another form, lstrip() can be done this way:

    char* lstrip (char* string) {
  
        if (string) {
        /* Trim off leading whitespace */
        while (*string == ' ') {
            string++;
        }
  
        return string;
    }
  

  Also, your plain return won't work because the function is supposed to return a char*.

These points are mostly designed-oriented:

• I'd recommend having len() return a size_t while making i the same type. This type is preferred for size functions (especially library ones) because it is unsigned (non-negatives), whereas int is signed (non-negatives and negatives).

• Although just another form, lstrip() can be done this way:

    char* lstrip (char* string) { 
  
        // skip and return right away if condition is not met
        if (string) {
        /* Trim off leading whitespace */
        while (*string == ' ') {
            string++;
        }
  
        return string;
    }
  

  Also, your plain return won't work because the function is supposed to return a char*.