c语言中函数体中的变量声明不能使用和形参相同的变量名

001、

[root@PC1 test]# ls
test.c
[root@PC1 test]# cat test.c
#include <stdio.h>

int max(int a, int b)                                   // 创建一个名为max的函数
{
        int k = 100;
        if(a > b)
        {
                 return a;
        }
        else
        {
                return b;
        }
}

int main(void)
{
        int x, y;

        puts("please input two integers.");
        printf("x: "); scanf("%d", &x);
        printf("y: "); scanf("%d", &y);

        printf("the large is %d\n", max(x,y));

        return 0;
}
[root@PC1 test]# gcc test.c -o kkk
[root@PC1 test]# ls
kkk  test.c
[root@PC1 test]# ./kkk
please input two integers.
x: 87
y: 34
the large is 87

 。

002、

[root@PC1 test]# ls
test.c
[root@PC1 test]# cat test.c           ## 测试程序
#include <stdio.h>

int max(int a, int b)                 // 创建一个函数max
{
        int a = 100;                  //声明一个和形参同名的变量
        if(a > b)
        {
                 return a;
        }
        else
        {
                return b;
        }
}

int main(void)
{
        int x, y;

        puts("please input two integers.");
        printf("x: "); scanf("%d", &x);
        printf("y: "); scanf("%d", &y);

        printf("the large is %d\n", max(x,y));

        return 0;
}
[root@PC1 test]# gcc test.c -o kkk                            ## 程序无法正常编译
test.c: In function ‘max’:
test.c:5:6: error: ‘a’ redeclared as different kind of symbol
  int a = 100;
      ^
test.c:3:13: note: previous definition of ‘a’ was here
 int max(int a, int b)
             ^

 。