Question

我似乎对一个简单的程序有问题，该程序应该计算文件中的各种字符类型。即使文件根本不为空，它也始终打印零。我认为它与指针有关，可能是错的。我还想知道在这种情况下是否需要初始化变量？

// fun.h

void count_char(FILE *f, unsigned *newl, unsigned *let, unsigned *num, unsigned *spec_char);

// main.c

#include <stdio.h>
#include "fun.h"

int main()
{
    unsigned newline = 0, number = 0, letter = 0, special_character = 0;
    char path[256];
    FILE *f_read;
    printf("Insert a file path: ");
    gets(path);
    f_read = fopen(path, "r");
    if(f_read == NULL)
    {
        perror("The following error occurred");
        return 1;
    }
    count_char(f_read, &newline, &number, &letter, &special_character);
    printf("File content:\n\tnewline - %u\n\tletters - %u\n\tnumbers - %u\n\tspecial characters - %u\n", newline, number, letter, special_character);
    return 0;
}

// fun.c

#include <stdio.h>
#include <ctype.h>

void count_char(FILE *f, unsigned *newl, unsigned *let, unsigned *num, unsigned *spec_char)
{
    char c;
    while((c = fgetc(f)) != EOF)
    {
        if(c == '\n')
            *newl++;
        else if(isalpha(c))
            *let++;
        else if(isdigit(c))
            *num++;
        else
            *spec_char++;
    }
    return;
}

Answer 1

当你做这样的事情时：*newl++;;会发生的是，首先，指针递增（即使其指向下一个存储位置），然后根据运算符优先级取消引用。

如果要取消引用然后递增，则必须使用括号，如下所示：(*newl)++;

无法递增解除引用指针的值

1 个答案: