CODEWITHSUNDEEP
cpointers
Aiden Cullo
Aiden Cullo

Reputation: 25

Expression result unused when incrementing a pointer

When I call this function I get the error even though they are being used. Can someone explain:

pointers.c:30:5: warning: expression result unused [-Wunused-value]
    *a++;
    ^~~~

pointers.c:39:9: warning: expression result unused [-Wunused-value]
        *s++;
        ^~~~

pointers.c:40:9: warning: expression result unused [-Wunused-value]
        *b++;
        ^~~~

pointers.c:48:7: warning: expression result unused [-Wunused-value]
      *s++;
      ^~~~

int strend(char *s, char *b){
  char *temp = b; 
  while(*s != '\0'){
    if(*s == *b){
      while(*s == *b && *b != '\0' && *s != '\0'){ 
        *s++;
        *b++;
        if(*b == '\0')
           printf("wrong");
        printf("compare: %c, %c\n", *s, *b);
        printf("equal: %d\n", *s == *b);
      }
    }
    else{
      *s++;
    }
    printf("check %c, %c\n", *s, *b);
    if(*b == '\0' && *s == '\0'){
      return 1;
    }
    else{
      b = temp;
    }
    if(*s == '\0')
      printf("bazinga");
  }
  return 0;
}

Upvotes: 1

Views: 1951

Answers (1)

Some programmer dude
Some programmer dude

Reputation: 409404

You dereference the pointer too, not only incrementing it. That dereference will give you the value pointed to by the old pointer (before the increment) but you don't use that value, leading to the warning.

Simple solution? Don't use the dereference operator *.

Upvotes: 5

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