無法將數組傳遞給函數。爲什麼不工作？

Question

我是C編程的初學者，我需要幫助。 這個c代碼沒有任何錯誤或警告，但我似乎無法讓數組將值傳遞給calcMagicNumber函數。我該如何解決？ 在此先感謝！

#include <stdio.h> 

//function prototypes 
void printHeader();     
void askForNumber();      
int calcMagicNumber(int num[], int size); 
void writeResults(char*, int, int);  
void goodbye();       

int main(){ 
    //assign the variables 
    char name[51];     //for user to input name 
    char option='Y';     //option for user to continue the program 
    int magicNumber=0;    //to calculate the magic number 
    int flag=0;  //to determine if the magic number is an even or odd number 
    int num[5]={0,0,0,0,0};     //for user to input the 5 numbers 

    printHeader(); 

    puts("Please enter your name"); 
    scanf("%[^\n]s", name); 


    do{ 

     //call the function calcMagicNumber to produce the magic number 
     magicNumber = calcMagicNumber(num, 5); 

     //determine if the magic number is an even number 
     if(magicNumber%2==0){ 
      flag=1; 
     } 
     else{ 
      flag=0; 
     } 

     //call function writeResults to print out the user's name, the magic 
number and whether the magic number is even 
     writeResults(name, magicNumber, flag); 

     fflush(stdin); //clear buffer 

     //ask user if he or she would like to go again 
     puts("Would you like to go again? [y/n]"); 
     scanf("%c", &option); 

     option = toupper(option); //to convert the user's input into capital 
letters 

    }while(option == 'Y'); 

    goodbye(); 

    return 0; 
} 

//function bodies 
void printHeader(){ 
    //print out name and chapter 3 - magic number 
    printf("Chapter 3- Magic Number \n"); 
    printf("Tan Su Fern\n\n"); 
} 

void askForNumber(){ 
    int i=1; 
    int num[5]={0,0,0,0,0}; 

    //ask user to input number 
    for(i=1;i<=5;i++){ 

     puts("Please enter a number."); 
     scanf("%d", &num[i]); 

    } 
    num[i]=i; 
    printf("\n%d, %d, %d, %d, %d", num[1], num[2], num[3], num[4], num[5]); 
} 

int calcMagicNumber(int num[], int size){ 
    int magicNumber=0; 

    //call askForNumber function for user to input 5 numbers 
    askForNumber(); 

    printf("\n%d, %d, %d, %d, %d", num[1], num[2], num[3], num[4], num[5]); 
    //calculate the magic number based on the numbers input by the user 
    magicNumber = (num[1]*num[5])-(num[2]+num[3]+num[4]); 

    return magicNumber; 
} 

void writeResults(char* name, int magicNumber, int flag){ 
    //print out the magic number and the user's name 
    printf("\nHi %s , your magic number is %d.\n", name, magicNumber); 

    //print out if the magic number is an even or odd number 
    if(flag==1){ 
     printf("This is an even number.\n\n"); 
    } 
    else{ 
     printf("This is an odd number.\n\n"); 
    } 
} 

void goodbye(){ 
    //say goodbye 
    printf("goodbye"); 
} 

Answer 1

問題是你的函數內的第二陣列askForNumber

void askForNumber() 
{ 
    int num[5] = { 0, 0, 0, 0, 0 }; 
    // ^^ 
} 

這第二陣列並存到，只要你是在函數中的主要定義的，但會再次銷燬一旦你離開功能。用戶的值將被分配給第二個數組，而第一個數組保持不變。

相反，需要進一步通過主的陣列（您傳遞給calcMagicNumber的那個）到askForNumber：

void askForNumber(int num[], size_t size) 
{ 
    // int num[5] = { 0, 0, 0, 0, 0 }; 
    //  ^^ drop this one! 
} 

邊注：在C（這是不同的，以C++），函數不接受任何參數實際上被聲明/定義爲：

void f(void); 
//  ^^^^ 

離開出空隙關鍵字使得能夠傳遞的參數任意數量的功能。試試這個：

void good(void) { } 
void bad() { } 

int main() 
{ 
    good(); 
    bad(1); 
    bad(1, 2, 3); 
    good(1); // <- this is the ONLY line that won't compile... 
} 

的void f()語法是哪裏函數參數，其中，隨後宣佈預ANSI C倍餘。不希望再使用這種語法。