如何对结构体类型的数组进行排序 - int 和 char

Question

查看代码中sorteraF的函数，我尝试对结构类型的数组进行排序。我想为name类型字符和varunummer类型int执行此操作。但是它不起作用。为了对我使用的名称进行排序sortAfterNames这也不起作用。

             //lager program lab 
             #include <stdio.h>
             #include <stdlib.h>
             #include <string.h> 
             #define WORDLENGTH 30
             #define MAX 10
             struct varor{ //VAROR STANDS FOR GOODS----------
                 int varunummer;
                 char namn[WORDLENGTH];
                 int lagersaldo; 
             };
             typedef struct varor Vara;
             Vara createVara(int varunummer, char namn[], int lagersaldo){  //CREATE THE GOODS
                 Vara v;
                 v.varunummer=varunummer;
                 strcpy(v.namn, namn);
                 v.lagersaldo=lagersaldo;
                 return v;
             }
           //register
             void regVaror( Vara reg[], int *pNrOfGoods){   //REGISTER THE GOODS
                 char confirm;
                 char namn[WORDLENGTH],
                      tmp[WORDLENGTH];
                 int varunummer, lagersaldo;
                 printf("nAre you sure you want to register new goods?n1: YES - (continue)n2: NO - (go back to menu)n");
                 scanf(" %c%*c", &confirm);// choose
                 switch(confirm){
                 case '1': 
                 do{
                     printf("Enter varunummer:");//varunummer stands for identify number of the good
                     gets(tmp); 
                     varunummer=atoi(tmp);
                     printf("Enter name:");
                     gets(namn);
                     printf("Enter Availability:");
                     gets(tmp);
                     lagersaldo=atoi(tmp);
                     reg[*pNrOfGoods]=createVara(varunummer,namn,lagersaldo);
                     (*pNrOfGoods)++;
                     printf("nRegister more goods?n1: YES - (continue)n2: NO - (go back to menu)n");
                     scanf(" %c%*c", &confirm);
                 }while(confirm=='1');
                 case '2': break;
                 }
             }
             //PRINTING THE GOODS ---------
            void printVara(Vara reg[], int nrOfGoods){
                int x;
                printf("nVarunummer t Namn ttt Lagersaldon");
                for(x=0;x<nrOfGoods;x++){
                    printf(" %d tt %s ttt %dn",reg[x].varunummer,reg[x].namn,reg[x].lagersaldo);
                }
            }
    //SORTING THE GOODS---------
             void sorteraF(Vara reg[], int length){
                 int i, j;
                     struct varor tmp;
                     for (i = 0; i < (length-1); i++){
                         for (j = 0; j < (length -1- i); j++){
                             if (reg[i].varunummer < reg[i + 1].varunummer){
                                 tmp = reg[j];
                                 reg[j] = reg[j + 1];
                                 reg[j + 1] = tmp;
                             } 
                         }
                     } 
             }
void sortAfterName(reg[]){
int i,j;
         char tmp[MAX];
         for(i=0;i<MAX;i++){
             for(j=i+1; j<MAX;j++){
                 if(strcmp(reg[i].namn, reg[i+1].namn) >0){
                     tmp=reg[i];
                     reg[i]=reg[i+1];
                     reg[i+1]=tmp[i];
                  }
              }
             int main(){
                 int run=1;
                 Vara vRegister[MAX];
                 int nrOfGoods=0;
                 while(run){
                    char choice;
                    printf("nttMeny - Lager Programnn
                    (1) Regrister new varornbbbb
                    (2) Print all varorn
                    (3) Sort varorn
                    (4) Avsluta programmetn");
                    scanf(" %c%*c", &choice);
                    if(choice=='1') regVaror(vRegister, &nrOfGoods);
                    if(choice=='2') printVara(vRegister, nrOfGoods);
                    if(choice=='3') sorteraF(vRegister, MAX);
                    else if(choice=='4') run=0;
                    printf("nnNumber of varor: %dn", nrOfGoods);

                 }
                 return 0;
             }

Answer 1

概述如何使用qsort()（这里没有理由重新发明轮子）：

#include <stdlib.h>
#include <string.h>
#define WORDLENGTH 30
struct varor
{
    int varunummer;
    char namn[WORDLENGTH];
    int lagersaldo; 
};
typedef struct varor Vara;
// comparison function for qsort, just compare the names with strcmp:
static int compareByName(const void *v1, const void *v2)
{
    return strcmp(((const Vara *)v1)->namn, ((const Vara *)v2)->namn);
}
// the same for the numbers
static int compareByNumber(const void *v1, const void *v2)
{
    int n1 = ((const Vara *)v1)->varunummer;
    int n2 = ((const Vara *)v2)->varunummer;
    if (n1 < n2) return -1;
    if (n1 > n2) return 1;
    return 0;
}
int main(void)
{
    Vara v[100];
    // populate v with data
    // to sort by name:
    qsort(v, sizeof v / sizeof *v, sizeof *v, compareByName);
    // to sort by number:
    qsort(v, sizeof v / sizeof *v, sizeof *v, compareByNumber);
}

sizeof v / sizeof *v这里的结果是元素的总数（这里为 100，在您的示例代码中可能是 10）——所以如果你不填充整个数组，请在此处传递使用的元素数。