試圖通過x，y，z作爲參數

Question

錯誤表示預期的主要表達式在int之前，在我稱爲foo的main行中。我不明白，以及如何解決它。我究竟做錯了什麼？

#include <stdio.h> 
#include <stdlib.h> 

int foo(int *a, int *b, int c) { 
    /* Set a to double its original value */ 
    *a = *a * *a; 
    /* Set b to half its original value */ 
    *b = *b/2; 
    /* Assign a+b to c */ 
    c = *a + *b; 
    /* Return c */ 
    return c; 
} 

int main() { 
    /* Declare three integers x, y, z and initialize them to 5, 6, 7 respectively */ 
    int x = 5, y = 6, z = 7; 
    /* Print the values of x, y, z */ 
    printf("X value: %d\t\n", x); 
    printf("Y value: %d\t\n", y); 
    printf("Z value: %d\t\n", z); 
    /* Call foo() appropriately, passing x, y, z as parameters */ 
    foo(int *x, int *y, int z); 
    /* Print the value returned by foo */ 
    printf("Value returned by foo: %d\t\n", foo(x, y, z)); 
    /* Print the values of x, y, z again */ 
    printf("X value: %d\t\n", x); 
    printf("Y value: %d\t\n", y); 
    printf("Z value: %d\t\n", z); 
    /* Is the return value different than the value of z? Why? */ 

    return 0; 
} 

Answer 1

你是不正確調用它，你需要把變量的地址傳遞的參數：另外

foo(&x,&y,z); 

，因爲你是按值傳遞ž不引用，你應該給它分配該函數的返回值（它看起來像那是你正在嘗試做的？）：

z=foo(&x,&y,z); 

Answer 2

你宣佈你的意思，其中的變量路過他們..

foo(&x, &y, z);