打印出c中最长的字符串

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]);

Answer 2

Your problem is in here:

max = strlen(argv[i]);
if(max < argv[i])
{
  max=argv[i];
}

You seem to be a bit confused about what max is for here. What you really want to do is:

• take strlen(argv[i]) , and store it in a variable
• check whether it is greater than max
• if it is, store it in max

Try translating that to C code and post what you come up with.

Answer 3

Did you mean:

int i;
int max = strlen(argv[0]);

for (i = 0; i < argc; ++i) 
{
    if (max < strlen(argv[i]))
    {
        max = strlen(argv[i]);
    }
}

Answer 4

int max = 0;//assuming  initial max length of 0. start loop from index 1 (index 0 is program name)
for(i = 1; i < argc; ++i) {

    int len = strlen(argv[i]);//get length of str
    if(max < len )
    {
       max=len;//store the new max length
    }
}