在main()中调用的C函数不返回值

Question

我正在使用一个C程序，它使用多个函数读取文本文件，并返回行数、空行、注释等。然而，当我在main()中调用多个函数时，只有第一个函数返回它的值。其他函数返回- 0。为什么？调用函数的正确方法是什么？

终端输出

示例代码：

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

int non_blank_lines(FILE *input);
int all_lines(FILE *input);

main (int argc , char **argv)
{
    char file_name[40];
    
    //prompting a user to enter a file name
    printf("Please enter a file name: ");
    scanf("%s", file_name);
    
    //opening and reading the file
    FILE *input = fopen(file_name, "r");
     
    //check if the entered file exists
    if (input == NULL) 
    { 
        printf("File %s does not exist!", file_name); 
        return 0; 
    } 

    //calling the functions and printing the output
    printf("The file %s has %d filled lines.\n", file_name, non_blank_lines(input));
    printf("The file %s has in total %d lines.\n", file_name, all_lines(input));
    
    
    fclose(input);
    return 0;
}

int non_blank_lines(FILE *input)
{
    int count = 0;
    char line[100];

    while(fgets(line, 100, input) != NULL)
    {
        if(strcmp(line, "\0") != 0 && strcmp(line, "\t") != 0 && strcmp(line, "\n") != 0)
            
            count = count + 1;
    }

    return count;
}

int all_lines(FILE *input)
{
    //searching for a new line character to count number of lines in a file
    int line_count = 0;
    char character;

    while((character = getc(input)) !=EOF)
    {
        if (character == '\n')
        line_count = line_count + 1;  
    }
        
    return line_count;
}

Answer 1

fgets()读取整行，因此getc()没有任何要读取的内容。