函数内数组大小计算错误 [英] Miscalculation of array size inside a function

问题描述

以下C程序:

int doStuff(int afm[]);

int main(){
    int afm1[9] = {1,2,3,4,5,6,7,8,9}; //size=9

    int afmLength = sizeof(afm1)/sizeof(int);
    printf("main: Length Of Array=%d\n", afmLength);  //9 OK

    int k = doStuff(afm1);

    system("PAUSE");
    return 0;   
}

int doStuff(int afm[]){
    int afmLength = sizeof(afm)/sizeof(int);    
    printf("doStuff: Length Of Array=%d\n", afmLength);  //1 WRONG

    return 1;
}

产生以下输出:

main: Length Of Array=9
doStuff: Length Of Array=1

为什么main中的数组大小计算正确，而函数内部却是错误的?

Why is the array size calculated correctly in main, but is wrong inside the function?

推荐答案

因为在 main 中有一个数组，而在函数中有一个指向该数组的指针.

Because in main you have an array and in the function you have a pointer to that array.

int doStuff(int afm[])

相当于

int doStuff(int *afm)

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