c - 如何从c(Ubuntu)中的文件中逐行读取？

Question

我试图从文件中逐行提取字符串，但它没有给我任何输出。该文件在 token 中包含一些单词。这是我的代码:

#include<stdio.h>
#include<string.h>
main(void)
{
    FILE *open;
    open = fopen("assembly.txt", "r");
    FILE *write;
    write = fopen("tokens.txt", "w");
    FILE *a;

    char ch;
    char *str;

    while ((ch = fgetc(open)) != EOF)
    {
        if (ch == 32 || ch == ',' || ch == '#')
            fprintf(write, "\n");

        else
            fprintf(write, "%c", ch);
    }

    a = fopen("tokens.txt", "r");

    while (!feof(a))
    {
        if (fgets(str, 126, a))
            printf("%s", str);
    }
}

我根本没有得到任何输出。程序执行成功，没有任何输出!

Answer 1

您的代码中有几个错误。首先:您没有关闭文件。第二:您对 str 执行了 fgets，但尚未分配，这将出现段错误。

修复后，现在您的代码是:

#include<stdio.h>
#include<string.h>
int main(void)
{
    FILE *open;
    open = fopen("assembly.txt", "r");
    FILE *write;
    write = fopen("tokens.txt", "w");
    FILE *a;

    char ch;
    char str[127];

    while ((ch = fgetc(open)) != EOF)
    {
        if (ch == 32 || ch == ',' || ch == '#')
            fprintf(write, "\n");

        else
            fprintf(write, "%c", ch);
    }    

    fclose(write);
    fclose(open);
    a = fopen("tokens.txt", "r");

    while (!feof(a))
    {
        if (fgets(str, 126, a))
            printf("%s", str);
    }
    fclose(a);
    return 0;
}