#include<stdio.h>
#include<string.h>
int main()
{
    int i,max;
    char sx[20];
    for(i=0;i<5;i++){        
        gets(sx);
        if(i>0)
            max=strcmp(sx-1,sx);
    }
    if(max==-1)
        printf("%s",sx);
    return 0;
}

#include<stdio.h>
#include<string.h>
int main()
{
    char sx[20];
    int i,big,small,num,blank,other;
    big=small=num=blank=other=0;
    gets(sx);
    for(i=0;i<strlen(sx);i++){
        if(sx[i]>=‘A‘&&sx[i]<=‘Z‘)
            big++;
        else if(sx[i]>=‘a‘&&sx[i]<=‘z‘)
            small++;
        else if(sx[i]>=‘0‘&&sx[i]<=‘9‘)
            num++;
        else if(sx[i]==‘ ‘)
            blank++;
        else
            other++;
    } 
    printf("大写字母有%3d个\n小写字母有%3d个\n空格有%3d个\n数字有%3d个\n其他字符有%3d个\n",big,small,num,blank,other);
    return 0;
}

#include<stdio.h>
#include<string.h>
struct student_list{
    char name[10];
    int aaa1;
    int aaa2;
    int aaa3;
    char number[10];
};
int count=0;
void search_student(struct student_list students[],char *name);
void new_student(struct student_list students[]);
void printf_student(struct student_list students[]);
void average_student(struct student_list students[],double average);
int main()
{
    int choice;
    double average;
    char name[10];
    struct student_list students[50]; 
    do{
        printf("******学生信息管理系统*******\n");
        printf("\t1:新建\n");
        printf("\t2:查询\n");
        printf("\t3:输出\n");
        printf("\t4:平均成绩\n");
        printf("\t0:退出\n");
        printf("请选择功能:");
        scanf("%d",&choice);
        switch(choice){
            case 1:
                new_student(students);
                break;
            case 2:
                printf("请输入要查找的学生姓名：");
                scanf("%s",name);
                search_student(students,name);
                break;
            case 3:                
                printf_student(students);
                break;
            case 4:
                average_student(students,average);
            case 0:
                break; 
        }        
    }while(choice!=0);
}
void new_student(struct student_list students[])
{
    int i;
    struct student_list s;
    if(count==50)
        printf("学生系统数据已满！");
    printf("请输入学生姓名:");
    scanf("%s",s.name);
    printf("请输入学生学号:");
    scanf("%s",s.number);
    printf("请输入学生三科成绩:");
    scanf("%d%d%d",&s.aaa1,&s.aaa2,&s.aaa3);
    students[count]=s;
    count++;
}
void printf_student(struct student_list students[])
{
    printf("系统中学生为:");
    int i;
    for(i=0;i<count;i++){
        printf("%s   %s   %d %d %d",students[i].name,students[i].number,students[i].aaa1,students[i].aaa2,students[i].aaa3);    
    }
            
}
void search_student(struct student_list students[],char *name)
{
    int i,a=0;
    if(count==0){
        printf("系统内无信息。");
        return;
    } 
    for(i=0;i<count;i++)
        if(strcmp(name,students[i].name)==0){
            a=1;
            break;
        }             
    if(a==1){
        printf("姓名:%s\t",students[i].name);
        printf("学号:%s\t",students[i].number);
        printf("分数:%d %d %d\n",students[i].aaa1,students[i].aaa2,students[i].aaa3);
    }
}
void average_student(struct student_list students[],double average)
{
    int i;
    for(i=0;i<count;i++)
        average=(students[i].aaa1+students[i].aaa2+students[i].aaa3)/3;
    printf("平均成绩=%.2lf\n",average);
    return;
}