如何调用按价值计算，调用由C基准的工作？ [英] How does call by value and call by reference work in C?

问题描述

在C程序，如何通过价值的工作做函数调用，以及如何通过参考工作不打电话，你如何返回一个值？

In a C program, how does function call by value work, and how does call by reference work, and how do you return a value?

推荐答案

按价值计算呼叫

void foo(int c){
    c=5; //5 is assigned to a copy of c
}

这样称呼它：

int c=4;
foo(c);
//c is still 4 here.

通过引用调用：传递一个指针。参考在C ++中存在

Call by reference: pass a pointer. References exist in c++

void foo(int* c){
    *c=5; //5 is assigned to  c
}

这样称呼它：

int c=0;
foo(&c);
//c is 5 here.

返回值

int foo(){
    int c=4;
     return c;//A copy of C is returned
}

通过参数返回

   int foo(int* errcode){

       *errcode = OK;

        return some_calculation
   }

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