在C中找到最长的单词

Question

I want to find longest string from array of strings by taking command line arguments. I can receive command line arguments, but what's wrong with my logic?

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

int main(int argc, char *argv[]) {

    int i;
    char *c = argv[1];
    int maxSize = strlen(argv[1]);

    for(i=2;i<=argc;i++){
        int len = strlen(argv[i]);
        if(len>maxSize){
            maxSize = len;
            c = argv[i];
        }
    }

    printf("Max length string : %s", c);
}

Answer 1

Your loop is running out-of-array.

It seems you understand the meanings of argc and argv, but you missed that argc is the number of the input arguments including the name of the process.

For the following input cases, you will receive 5 for argc and the last argument string, 'flow', is found in argv[4].

a.out hello statck over flow

However, your code will run into argv[5] which is not the part of argments, and can result in undefined behavior.

The loop in the code should be changed like,

for(i=1; i<argc; i++)
{
}

Answer 2

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

int main(int argc, char *argv[]) {
    if (argc == 1) {
        printf("No arguments provided");
        return 1;
    }

    int maxLength = 0;
    int maxIndex = 0;

    int i;
    char* word;
    for (i = 1; i < argc; i++) {
        word = argv[i];
        int length = strlen(word);
        if (length > maxLength) {
            maxLength = length;
            maxIndex = i;
        }
    }

    printf("Max length is %d for string: %s\n", maxLength, argv[maxIndex]);
    return 0;
}

Answer 3

Here are some comments to your code, hope it helps.