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

//记录学生数
int count;

//定义学生信息
struct student
{
    int num;
    char name[10];
    float Maths[2];
    float English[2];
    float Computer[2];
    double finallyscore[3];
    struct student *next;
};

//函数声明
struct student *create();
void Delete(struct student *pHead);
bool cheak2(struct student *pHead,int number);    

void main()
{
    int option;
    struct student *pHead=NULL;
    printf("请选择:");
    scanf("%d",&option);
    while(true)
    {
        switch(option)
        {
        case 1: pHead=create();break;
    
        case 3:    Delete(pHead);break;
        
        case 0: exit(0);break;
        default :
            {
                printf("输入错误,请重新输入:");
                scanf("%d",&option);
            }
        }
        getch();
        printf("请选择:");
        scanf("%d",&option);
    }    
}

//创建信息
struct student *create()
{
    struct student *pHead;
    struct student *pNew,*pEnd;
    pHead=NULL;
    count=0;
    pEnd=pNew=(struct student*)malloc(sizeof(struct student));
    while(true)
    {
        printf("请输入学生信息(输入0退出)\n\n");

        printf("学号:");
        scanf("%d",&pNew->num);

        while(pNew->num<0)
        {
            printf("输入错误，请重新输入学号:");
            scanf("%d",&pNew->num);
            getch();
        }

        if(pNew->num==0)
            goto end;

        printf("学生姓名:");
        scanf("%s",&pNew->name);
        printf("数学平时成绩、考试成绩:");
        scanf("%f%f",&pNew->Maths[0],&pNew->Maths[1]);
        printf("英语平时成绩、考试:");
        scanf("%f%f",&pNew->English[0],&pNew->English[1]);
        printf("计算机平时成绩、考试成绩:");
        scanf("%f%f",&pNew->Computer[0],&pNew->Computer[1]);
        printf("\n");
            
        //计算综合成绩
        pNew->finallyscore[0]=pNew->Maths[0]*0.3+pNew->Maths[1]*0.7;
        pNew->finallyscore[1]=pNew->English[0]*0.3+pNew->English[1]*0.7;
        pNew->finallyscore[2]=pNew->Computer[0]*0.3+pNew->Computer[1]*0.7;

        count++;
        if(count==1)
        {
            pNew->next=pHead;
            pHead=pNew;
            pEnd=pNew;
        }
        else
        {
            pNew->next=NULL;
            pEnd->next=pNew;
            pEnd=pNew;
        }
        pNew=(struct student*)malloc(sizeof(struct student));

    }
    end:
        free(pNew);
        return pHead;    
}

//删除学生信息
void Delete(struct student *pHead)
{
    int a,i;
    if(pHead!=NULL)
    {
        printf("请输入要删除的学生学生学号:");
        scanf("%d",&a);
        if(check2(pHead,a))
        {
            struct student *pTemp,*pPre;
            pTemp=pHead;
            for(i=1;i<a;i++)
            {
                pPre=pTemp;
                pTemp=pTemp->next;
            }
            pPre->next=pTemp->next;
            free(pTemp);
            count--;
        }
           else
            printf("该学生不存在！");
    }
    else
        printf("该系统不存在任何信息，请先建立!");
}

//检查是否存在该学生信息
bool check2(struct student *pHead,int number)
{
    struct student *ptemp=pHead;
    if(pHead==NULL)
    {
        printf("没有相关学生信息\n");
        return false;
    }
    else
    {
        while(ptemp!=NULL)
        {
            if(ptemp->num==number)
            {
                return true;
                break;
            }
            ptemp=ptemp->next;
        }
        return false;
    }

}

C:\Users\acer\Desktop\a.cpp(121) : error C2065: 'check2' : undeclared identifier
C:\Users\acer\Desktop\a.cpp(143) : error C2373: 'check2' : redefinition; different type modifiers

你看一下声明  大概是拼写错误吧

声明检查了一下，似乎没有错。

如果出现这类问题，一般情况是什么造成的，大概怎么解决这类问题呢？

你要是我教的肯定会挨顿臭骂
函数声明写的是cheak2
定义的是check2，你说一样吗？

呵呵

,太sorry了，感谢你们