c语言中声明数组时， 元素个数必须使用常量表达式

 

001、

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

int main(void)
{
        int var1 = 5;              // 初始化一个变量var1

        int array1[var1] = {3,5,8,4,9};    // 初始化数组

        return 0;
}
[root@PC1 test]# gcc test.c -o kkk          ## 无法进行编译，说明声明数组个数时，必须使用常量表达式
test.c: In function ‘main’:
test.c:7:2: error: variable-sized object may not be initialized
  int array1[var1] = {3,5,8,4,9};
  ^
test.c:7:2: warning: excess elements in array initializer [enabled by default]
test.c:7:2: warning: (near initialization for ‘array1’) [enabled by default]
test.c:7:2: warning: excess elements in array initializer [enabled by default]
test.c:7:2: warning: (near initialization for ‘array1’) [enabled by default]
test.c:7:2: warning: excess elements in array initializer [enabled by default]
test.c:7:2: warning: (near initialization for ‘array1’) [enabled by default]
test.c:7:2: warning: excess elements in array initializer [enabled by default]
test.c:7:2: warning: (near initialization for ‘array1’) [enabled by default]
test.c:7:2: warning: excess elements in array initializer [enabled by default]
test.c:7:2: warning: (near initialization for ‘array1’) [enabled by default]

 。

 

002、验证

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

int main(void)
{
        int var1 = 5;

        int array1[5] = {3,5,8,4,9};           // 这里数组个数修改为常量

        return 0;
}
[root@PC1 test]# gcc test.c -o kkk           ## 可以编译了
[root@PC1 test]# ls
kkk  test.c

 。

 

003、使用对象式宏

[root@PC1 test]# ls
test.c
[root@PC1 test]# cat test.c
#include <stdio.h>
#define NUMBER 5                                    // 定义了一个对象式宏

int main(void)
{
        int var1 = 5;

        int array1[NUMBER] = {3,5,8,4,9};           //使用对象式宏变量

        return 0;
}
[root@PC1 test]# gcc test.c -o kkk                  ## 编译
[root@PC1 test]# ls
kkk  test.c

 。