c - How to switch characters in a string two characters at a time -

i working on first attempt @ learning c. want know if possible change characters of string two. meaning if have word: "hello", how set function change string to: "hlelo". have method called

void word_reverse(char* str) {     strrev(str);//changes whole string in reverse } 

how make change 2 characters in string @ time? many in advance.

i'm not working out in front of compiler you'll have work make run, should started @ least.

char *resersi(char *string) {   char *start = string;   char *end = string;    // move end pointer end (c-style strings end in '\0')   while (*end != 0) end ++;    // move end pointer 1 away end (we don't want swap '\0')   end--;    // slide start pointer , end pointer inwards until overlap or cross.   while (start < end) {      // swap values      char temp = *end;      *end = *start;      *start = temp;        // slide pointers      start++;      end--;   }    return string; } 

here basic outline of you'll need do.