C 程序没有 output 任何东西

Question

This program is supposed to open a text file, then search for given words in argv . It will search for the words line by line and if it finds one of the given words in that line the program should print it.

This the code I wrote for it:

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

int existe_mot_cle(char s[1024], int argc, char *argv[])
{
    int test = 0;
    for (int i = 2; i < argc; i++)
    {
        if (strstr(s, argv[i]))
            test = 1;
        break;
    }
    return test;
}

int open_file(char *argv[], FILE *fp)
{
    fp = fopen(argv[1], "a");
}

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

{
    FILE *fp;
    char s[1024];

    if (!open_file(argv, fp))
        return 0;

    while (fgets(s, 1024, fp))
    {
        if (existe_mot_cle(s, argc, argv))
            printf("%s", s);
    }
    fclose(fp);
}

The problem is when I run it, nothing happens and I don't know why. I am new to the C language. Can someone give me the solution and explain it please?

Answer 1

You are break ing the for loop right after the first if statement is executed. You should surround it with curly braces:

int existe_mot_cle(char s[1024], int argc, char *argv[])
{
    int test = 0;
    for (int i = 2; i < argc; i++)
    {
        if (strstr(s, argv[i])) {
            test = 1;
            break;
        }
    }
    return test;
}

You can make it simpler and more generic:

bool existe_mot_cle(char s[1024], size_t size, const char *ss[])
{
    for (size_t i = 0; i < size; i++) {
        if (strstr(s, ss[i]))
            return true;
    }
    return false;
}

Also, your open_file() should return an int , but it is not returning anything. Better remove it from your code since it serves no purpose:

int main(int argc, const char *argv[])
{
    if (argc < 3) {
        printf("Usage: %s [file] [words]\n", argv[0]);
        return 0;
    }
    
    const char *filename = argv[1]; // More meaningful
    const char **otherarg = argv + 2;
    
    FILE *fp = fopen(filename, "r");
    
    if (!fp) {
        printf("Could not open %s.\n", filename);
        return 0;
    }
    
    char s[1024];
    while (fgets(s, sizeof s, fp))
    {
        if (existe_mot_cle(s, argc-2, otherarg)) // I'm using the second "simpler" version
            printf("%s", s);
    }
    
    fclose(fp);
}