使用标准I/O来计算字符数

#include <stdio.h>
#include <stdlib.h> // exit() prototype

int main(int argc, char *argv[])
{
    int ch;         // place to store each character as read
    FILE *fp;       // file pointer
    unsigned long count = 0;
    if (argc != 2)
    {
        printf(Usage: %s filename\n, argv[0]);
        exit(EXIT_FAILURE);
    }
    if ((fp = fopen(argv[1], r)) == NULL)
    {
        printf(Can't open %s\n, argv[1]);
        exit(EXIT_FAILURE);
    }
    while ((ch = getc(fp)) != EOF)
    {
        putc(ch,stdout);  // same as putchar(ch);
        count++;
    }
    fclose(fp);
    printf(File %s has %lu characters\n, argv[1], count);

    return 0;
}