代码如下
#include
#include
#include
struct student
{
    char Num[10];
    char Name[15];
    int type;
    int total;
};
int main()
{
    struct student stud1[100];
    int i,j,n;
    int x=1;
    char k[10];
    printf("input how many student you need to input:");
    scanf("%d",&n);
    printf("input number\tname\tstudenttype(major 1. in science 2.in arts)\ttotal:\n");
    for(i=0;i<N;I++)
    {
        scanf("%s\t",&stud1[i].Num);
        scanf("%s\t",&stud1[i].Name);
        scanf("%d\t",&stud1[i].type);
        scanf("%d\t",&stud1[i].total);
    }
    printf("\n");
    if(x==1)
    {
       printf("input the number you search:");
       scanf("%s",&k);
       printf("\n");
       for(i=0;i<N;I++)
       {
          if(strcmp(stud1[i].Num,k)==0)
          {
             printf("%s\t",stud1[i].Num);
             printf("%s\t",stud1[i].Name);
             printf("type %d\t\t",stud1[i].type);
             printf("%d",stud1[i].total);
             printf("\n");
          }
       }
       printf("input 1 to input again or 2 to out:");
       scanf("%d",&x);
       printf("\n");
    }
    return 0;
}

中间没问题，有的话大概只是逻辑错误

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
struct student
{
    char Num[10];
    char Name[15];
    int type;
    int total;
};
int main()
{
    struct student stud1[100];
    int i,j,n;
    int x=1;
    char k[10];
    printf("input how many student you need to input:");
    scanf("%d",&n);
    printf("input number\tname\tstudenttype(major 1. in science 2.in arts)\ttotal:\n");
    for(i=0;i<n;i++)
    {
        scanf("%s\t",&stud1[i].Num);
        scanf("%s\t",&stud1[i].Name);
        scanf("%d\t",&stud1[i].type);
        scanf("%d\t",&stud1[i].total);
    }
    printf("\n");
    if(x==1)
    {
       printf("input the number you search:");
       scanf("%s",&k);
       printf("\n");
       for(i=0;i<n;i++)
       {
          if(strcmp(stud1[i].Num,k)==0)
          {
             printf("%s\t",stud1[i].Num);
             printf("%s\t",stud1[i].Name);
             printf("type %d\t\t",stud1[i].type);
             printf("%d",stud1[i].total);
             printf("\n");
          }
       }
       printf("input 1 to input again or 2 to out:");
       scanf("%d",&x);
       printf("\n");
    }
    return 0;
}

if(x==1)
    {
       printf("input the number you search:");
       scanf("%s",&k);
       printf("\n");
       for(i=0;i<n;i++)
       {
          if(strcmp(stud1[i].Num,k)==0)
          {
             printf("%s\t",stud1[i].Num);
             printf("%s\t",stud1[i].Name);
             printf("type %d\t\t",stud1[i].type);
             printf("%d",stud1[i].total);
             printf("\n");
          }
       }
       printf("input 1 to input again or 2 to out:");
       scanf("%d",&x);
       printf("\n");
    }
    return 0;
这一段中的两个scanf都跳过了