c - 为什么在 C 中输入为 0 时我的 getc() 总是返回 30？

Question

int main(void){
    char buffer[5] = {0};  
    int i;
    FILE *fp = fopen("haha.txt", "r");
    if (fp == NULL) {
    perror("Failed to open file \"mhaha\"");
    return EXIT_FAILURE;
    }
    for (i = 0; i < 5; i++) {
        int rc = getc(fp);
        if (rc == EOF) {
            fputs("An error occurred while reading the file.\n", stderr);
            return EXIT_FAILURE;
        }
    buffer[i] = rc;
    }
    fclose(fp);
    printf("The bytes read were... %x %x %x %x %x\n", buffer[0], buffer[1], buffer[2], buffer[3], buffer[4]);
    return EXIT_SUCCESS;
}

我在我的 haha​​.txt 文件中放了八个 0，当我运行这段代码时，它总是给我:

The bytes read were... 30 30 30 30 30

谁能告诉我为什么？

Answer 1

因为 '0' == 0x30

字符“0”是 0x30 (ascii)。