无法更新顺序访问文件中的记录

Question

我在修改顺序访问文件中的记录方面遇到了一些问题。当我在文件中有2条记录，并且我更新第二条记录时，它会显示：

enter model code to update
RECORD UPDATED

但是当我打开文件时，它只显示第一条记录。

void edit(void){

    char mcode[20]; //model code for car
    char mname[20]; //name of car
    int quantity; //how many of cars are in stock
    float cost; //cost to make the car
    float sellingprice; //price of the car

    char code[20];

    FILE *fp;
    FILE *temp;
    printf("enter model code to update:");
    scanf("%s",code);

        fp=fopen("stock.txt","r");
        temp=fopen("temp.txt","w");
        rewind(fp);

         while(fscanf(fp,"%s %s %f %f %d\n",mcode,mname,&cost,&sellingprice,&quantity)==5){

         fprintf(temp,"%s %s %.2f %.2f %d\n",mcode,mname,cost,sellingprice,quantity);

             if (strcmp(code,mcode) == 0) {
             printf("Enter quantity : ");
             scanf("%d",&quantity);                   
             fprintf(temp,"%s %s %.2f %.2f %d\n",mcode,mname,cost,sellingprice,quantity);       
             }

         fclose(fp);
         fclose(temp);
         }
         remove("stock.txt");
         rename("temp.txt", "stock.txt");

Answer 1

fclose语句应该在while循环之外。

同样，当code = mcode时，两个fprintf命令都将被执行。试试这个

while(fscanf(fp,"%s %s %f %f %d\n",mcode,mname,&cost,&sellingprice,&quantity)==5){

    if (strcmp(code,mcode) == 0) {
        printf("Enter quantity : ");
        scanf("%d",&quantity);                   
    }

    fprintf(temp,"%s %s %.2f %.2f %d\n",mcode,mname,cost,sellingprice,quantity);  
 }
 fclose(fp);
 fclose(temp);