#include <stdio.h>
int main(void)
{
    char buf[4];
    int cnt=0;

    cnt = snprintf(buf, sizeof(buf), "(%x)", 0xF123);

    printf("buf = %s\n", buf);
    printf("cnt = %d\n", cnt);
    return 0;
}

上述代码的运行结果,snprintf()返回值 cnt = 6大于buf的实际字节数:

buf = (f1
cnt = 6
按 <RETURN> 来关闭窗口...

继续测试

修改buf数组字节数(例如改为2)：

#include <stdio.h>
int main(void)
{
    char buf[2];
    int cnt=0;

    cnt = snprintf(buf, sizeof(buf), "(%x)", 0xF123);

    printf("buf = %s\n", buf);
    printf("cnt = %d\n", cnt);
    return 0;
}

char型数组char buf[4];无论分配多少个字节, 运行结果cnt都等于6!

buf = (
cnt = 6
按 <RETURN> 来关闭窗口...