c - 使用 fread 的代码中是否存在错误

Question

int main()
{
    FILE *read_fp;
    char buffer[BUFSIZ + 1];
    int chars_read;

    memset(buffer, '\0', sizeof(buffer));
    read_fp = popen("cat popen*.c | wc -l", "r");
    if (read_fp != NULL) {
        chars_read = fread(buffer, sizeof(char), BUFSIZ, read_fp);
        while (chars_read > 0) {
            buffer[chars_read - 1] = '\0';
            //buffer[chars_read] = '\0';
            printf("Reading:-\n %s\n", buffer);
            chars_read = fread(buffer, sizeof(char), BUFSIZ, read_fp);
        }
        pclose(read_fp);
        exit(EXIT_SUCCESS);
    }
    exit(EXIT_FAILURE);
}

fread() returns the number of items successfully read

我认为下面这行应该改成

buffer[chars_read - 1] = '\0';

到

buffer[chars_read] = '\0';

我做对了吗？

Answer 1

您是否尝试以 NULL 终止读取的字符串？如果是这样，那么是的，buffer[chars_read] = '\0'; 将是做到这一点的方法。

除此之外，如果你这样做的话，你的循环结构会更容易理解

do (
    chars_read = fread(....);
    if ( chars_read > 0) { 
       buffer[chars_read] = '\0';
       printf(....);
    }
} while (chars_read > 0);

或更传统

while ((chars_read = fread(....)) > 0) {
       buffer[chars_read] = '\0';
       printf(....);
}