Question

对于下面的函数，我必须按年龄按降序排序一系列员工，并且需要大小但不能将它放在函数变量中，我的老师告诉我通过在main中执行此操作来计算大小但是对于循环用j中的它告诉我elementSize可以在这个函数中使用unitialized。在main中它表示int elementSize =“”elementSize是一个未使用的变量。

int elementSize = sizeof(employeeList)/sizeof(Employee);//getting the size of the list

主

#include "lab10.h"

int main() {

Employee employeeList[10000];
readfile(employeeList);

clock_t start,end;
double cpu_time_used;
start = clock();

int elementSize = sizeof(employeeList)/sizeof(Employee);//getting the size of the list
bubbleSort(employeeList);//call bubble sort function to sort list in descending order
printList(employeeList, 25);
end = clock();
cpu_time_used = (double)(end-start)/CLOCKS_PER_SEC*1000;
printf("Time used to compute sorting was %f ms.\n",cpu_time_used);


int bin30=binSearch(employeeList, 0, 9999, 30);//binary search for people of the age of 30
if(bin30== -1){
 printf("employees not found!\n");//if employee of age 30 arent found
} else {
 printf("%s %s %d %d\n", employeeList[bin30].fname, employeeList[bin30].lname, employeeList[bin30].age, employeeList[bin30].salary); //print out employees info
 printf("element present at index %d", bin30);
 printf("time used is %f ms\n\n",cpu_time_used);//record time 
}

 int bin130=binSearch(employeeList, 0, 9999, 130);//binary search for people of the age of 30
   if(bin130== -1){
   printf("employees not found!\n");//if employee of age 130 arent found
     } else {
    printf("%s %s %d %d\n", employeeList[bin130].fname, employeeList[bin130].lname, employeeList[bin130].age, employeeList[bin130].salary); //print out employees info
    printf("element present at index %d", bin130);
    printf("time used is %f ms\n\n",cpu_time_used);//record time 
  }

   return 0;
}

void bubbleSort(Employee employeeList[]) {

   int swap;
   int i=0;
   int j=0;
   for(i=0; elementSize > i; i++) {//for loop to sort 
     for(j=0; elementSize > j ;j++) {
        if(employeeList[j+1].age > employeeList[j].age) {//comparing the two values
           swap = employeeList[j].age;//swapping the temp variable with the employee
           employeeList[j].age= employeeList[j+1].age;//setting the lower employeee to [j]
           employeeList[j+1].age = swap;//setting the higher employee to [j+1]
        }//end of if statement
     }//end of second for loop
   }//end of first for loop

}

#include "lab10.h"

//This function reads from a file and creates an array of Employee structure containing their information. 

void readfile(Employee employeeList[]){
FILE *fp;
fp = fopen("employeeData.csv", "r");
int i = 0;
if (fp) {
      while (i<10000){
         fscanf(fp, "%[^,],%[^,],%d,%d\n",employeeList[i].fname,employeeList[i].lname,&employeeList[i].age,&employeeList[i].salary);
         i++;
       }
   }

  fclose(fp);
}


 void printList(Employee employeeList[], int size)
{  
int i=0;
for(i=0; i<size; i++)//going through the first 25 elements of the array
{
printf("%d ", employeeList[i].age);//printing off the elements
}
}

int binSearch(Employee employeeList[], int first, int last, int age)
 {
if(first > last){
 return -1;//base case
 }
 int mid= (first + last)/2;//finding middle of the array

if(age > employeeList[mid].age)
   return binSearch(employeeList, mid+1, last, age);//searching for high in 
  binary search through recursion
 else if(age < employeeList[mid].age)
 return binSearch(employeeList, first, mid-1, age);//searching for low in binary search through recursion
 else 
 return mid;//return the expected value

}

Answer 1

在此代码中，您实际上有两个名为elementSize的变量，一个是bubbleSort的全局变量，另一个是elementSize的本地变量。局部变量阴影全局变量，意味着全局变量不可见。只有本地可见，并且本地从未初始化。

删除本地.... Application.ScreenUpdating = False ShowPDFs "C:\Test\Working\", ws ws.UsedRange.EntireColumn.AutoFit Application.ScreenUpdating = True End Sub ------------------------------ Private Sub ShowPDFs(ByRef fsoPath.......变量，全局变量将变为可见并将被使用。

功能中未初始化的变量

1 个答案: