C程序不編譯

Question

我需要找到最大的數字（這是一個雙）。我的計劃中有什麼問題？它不是編譯。

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

void dobig(double *parr[5],int *len,double *big); 

void main() 
{ 
    double *big; 
    double arr[5]={1.00,2.321,3.54337,4.333333,5.5555555}; 
    double *parr=&arr[5]; 
    int size=sizeof(arr)/sizeof(int); 
    int *len=&size; 
    dobig(parr,len,big); 
    printf("the largest number is %p/n",*big); 
    system("pause"); 
} 

void dobig(double *parr,int *len,double *big) 
{ 
    int i; 
    double pbig=*parr; 
    for(i=0;i>*len;i++) 
    { 
     if(pbig<*(parr+i)) 
     { 
      pbig=*(parr+i); 
     } 
     *big=pbig; 
    } 
} 

Answer 1

這裏有一個問題：

double *parr=&arr[5]; 

arr只有5個元素。從0所以有效的索引範圍 - 4

我評論過裏面的代碼有關的問題：

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

void dobig(double *parr,int *len,double *big); // Prototype didn't match. You want to 
     // pass a pointer, not an array of pointers. 

    int main(int argc, char *argv[]) // Standard way to write main() 
    { 
    double big; 
    double arr[5]={1.00,2.321,6.54337,4.333333,5.5555555}; 

    double *parr=&arr[0]; // If you want to loop through the array 
      //in dobig(), you have to pass the pointer to the first element or 
      //char *parr=arr; is also fine. 

    int size=sizeof(arr)/sizeof(double); // You want to know how many double's 
        // are there in the array. So use sizeof(double) 
    int *len=&size; 
    dobig(parr,len,&big); 
    printf("the largest number is %f\n",big); // To print a double, 
            //use %f. %p is for pointer. 
    } 

    void dobig(double *parr,int *len,double *big) 
    { 
    int i; 
    double pbig=*parr; 
    for(i=0;i<*len;i++) // Here it doesn't enter the 
       // loop at all due to incorrect condition. 
    { 
     if(pbig<*(parr+i)) 
     { 
      pbig=*(parr+i); 
     } 
    } 
    *big=pbig; 
    } 

Answer 2

變化

void dobig(double *parr[5],int *len,double *big); 

到

void dobig(double *parr, int *len, double *big); 

注：我建議不要使用void main但是int main

Answer 3

U正在傳遞一個數組，因此您需要在dobig函數中使用雙指針

這裏是您的代碼，並進行了必要的更正。

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

void dobig(double *parr[5],int *len,double *big); 

int main() 
{ 
double *big; 
double arr[5]={1.00,2.321,3.54337,4.333333,5.5555555}; 
double **parr=&arr[5]; 
int size=sizeof(arr)/sizeof(int); 
int *len=&size; 
dobig(parr,len,big); 
printf("the largest number is %p/n",*big); 
system("pause"); 
} 

void dobig(double **parr,int *len,double *big) 
{ 
int i; 
double pbig=**parr; 
for(i=0;i>*len;i++) 
{ 
if(pbig<**(parr+i)) 
{ 
    pbig=**(parr+i); 
} 
*big=pbig; 
} 
}