Question

Given any number of program parameters input into the command-line, calculate the length of each one, and lastly output the longest string. Here is my code, but it seems to be wrong.

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[]) {
  size_t maxlen = 0, len;
  int i;
  int longest;


  for (i = 1; i < argc; i++) {
   len = strlen(argv[i]);
     if (len > maxlen) 
       longest = argv[i];
  }

  printf("The longest string is %s. \n", longest);

  return 0;
}

Answer 1

Mistakes:

One. char max; ... max = strlen(argv[i]); wrong; strlen() returns size_t and not a char.

Two: if(max < argv[i]) also wrong, you’re comparing the length of the string with a pointer to the string. That doesn’t even make sense. What you probably want is

size_t maxlen = 0, len;
int i, maxindex = 0;

for (i = 1; i < argc; i++) {
    len = strlen(argv[i]);
    if (len > maxlen) {
        maxlen = len;
        maxindex = i;
    }
}

printf("The longest string is '%s'\n", argv[maxindex]);