c - 迭代文件时如何通过元素索引循环而不是逐个字符进行迭代

Question

#include <stdio.h>

int main(int argc, char **argv) {
    int c;
    FILE *file;
    file = fopen(argv[1], "r");
    if (file) {

        while ((c = getc(file)) != EOF) {
            if (c != 'a') {
                putchar(c);
            }
        }


    }
}

基本上，程序只是将一个文件作为标准输入，然后删除每个 a 并打印到标准输出。例如

$ gcc -Wall removeA.c
$ echo 123a >file1
$ ./a.out file1
123

我的问题是，如何使代码通过它的索引位置来获取它的长度，而不是通过字符来获取它的长度。类似下面的东西(它不起作用)

#include <stdio.h>

int main(int argc, char **argv) {
    int c;
    FILE *file;
    file = fopen(argv[1], "r");
    int i = 0;
    if (file) {

        while (i < len) {
            if (c[i] != 'a') {
                putchar(c[i]);
            }
            i++;
        }


    }
}

Answer 1

这样的事情应该让你开始......

FILE *fp = fopen(argv[1], "r");
if (fp)
{
  fseek(fp, 0, SEEK_END);
  size_t flen = ftell(fp);
  fseek(fp, 0, SEEK_SET);
  char *fbuf = (char*)malloc(flen + 1); // +1 to add a nul-term at the end
  if (!fbuf)
  {
     fprintf(stderr, "Out of memory trying to read file\n");
     exit(1);
  }
  if (fread(fbuf, 1, flen, fp) != flen) // read the whole file at once
  {
     fprintf(stderr, "Error reading file\n");
     exit(1);
  }
  fbuf[flen] = '\0'; // nul-term the buffer in case you use "str" functions on it
  fclose(fp);
  ...