#include<stdio.h>
int main()
{
    int cj;
    scanf("%d",&cj);
    if(cj>100||cj<0)
     printf("输入错误");
    else
       if(cj>=70);
           if(cj>=80);
           if(cj>=90)
             printf("优");
           else
             printf("良");
         else
           printf("好");
       else
         if(cj>=60)
          printf("合格");
         else
          printf("挂科");
            
}
想做个成绩的评估的 这个它说[Error] 'else' without a previous 'if'

if(cj>=70)和if(cj>=80)后面的分号删掉

#include<stdio.h>
int main()
{
    int cj;
    scanf("%d",&cj);
    if(cj>100||cj<0)
    printf("输入错误");
    else
    {
        if(cj>=70)
        {
            if(cj>=80)
            {
                if(cj>=90)
                printf("优");
                else
                printf("良");
            }
            else
           printf("好");
        }
         else
         {
             if(cj>=60)
                 printf("合格\n");
             else
                 printf("挂科\n"); 
         }
    }
             return 0;
}

稍微改了下，应该看起来舒服一点

为什么要以 70分 分成两部分？

#include <stdio.h>

int main( void )
{
    int score;
    if( scanf("%d",&score)!=1 || score>100 || score<0 )
        puts( "输入错误" );
    else if( score >= 90 )
        puts( "优" );
    else if( score >= 80 )
        puts( "良" );
    else if( score >= 70 )
        puts( "好" );
    else if( score >= 60 )
        puts( "合格" );
    else
        puts( "挂科" );

    return 0;
}

这个风格写法清楚明了

还可以这样,成绩等级区间统一均等划分这样会好处理一点,加了个"满分",把"满分"改成"优"这样就和题主的输出可以说是一样了~

#include <stdio.h>

int main( void )
{
    unsigned score;
    const char* s[]={"满分","优","良","好","合格","挂科"};
    
    if (scanf("%u",&score)!=1||score>100)
        puts("输入错误");
    else
        puts(score>59?*(s+10-(score/10)):*(s+sizeof (s)/sizeof (*s)-1));

    return 0;
}

[此贴子已经被作者于2018-4-14 19:16编辑过]

记得结构体可以用某种方法隐藏变量(例如struct Student{int:10};这样匿名声明)~
然后按照这个题目来做一个关于获取隐藏参数信息的,最近看了一下数据库,这可以算是一个小型的数据管理结构模式了~
而且这还是相对于处理单1个学生的情况,其实改改也可以多个,但由于具体实现结构会使结构体Student里面的参数有冗余,所以这只是对一个学生对象操作比较合适,有兴趣的可以看看获取匿名变量的方法~

#include <stdio.h>
#include<stdlib.h>
#include<string.h>
#include<limits.h>
#include<stdarg.h>
#include<assert.h>

#pragma pack (1)

#define __OK 0
#define __ERROR 1
#define __EFAULT 2
#define __UN_INIT 3

 
#ifndef IS_ERR
#define IS_ERR(E,RET)    \
    do    \
    {    \
        if (E)    \
            return RET;    \
    }while (0)    
#endif

#ifndef INT_BIT
#define INT_BIT  \
    (sizeof ( int )*CHAR_BIT)
#endif

#define __PARA_LIST( S )    \
    ((( int* )(S)+1))

#define __PARA_NUM_ID( S,N )    \
    (( int* )(( int* )(*__PARA_LIST(S))+(N)-1))

#define __PARA_ID( S,N )    \
    ( ( char* )(__PARA_LIST(S)+1)+*__PARA_NUM_ID((S),(N)))

#define __PARA_DATA( S ,N,TYPE )    \
    (*(( TYPE* )__PARA_ID((S),(N))))

void nodeMal( void**,size_t );
void nodeFree( void** );

typedef int Status;
typedef struct Student Student;
typedef const struct Stu_Metion Stu_Metion;

typedef struct Information Information;

static void _Init_Student( size_t,Student**,... );

Status newStudent( const Information*,Student** );

Status setScore( const Student* );

Status getScore( const Student*,unsigned char* );

Status printLevel(  const Student* );

Status dropStu( Student** );

struct Student
{
    #define __PARA_LEN int
    #define __PARA_LOCATION int

    #define __STATUS int
    
    #define __INF int

    #define __LEVEL int
    #define __SCORE int

    __PARA_LEN: INT_BIT;
    __PARA_LOCATION: INT_BIT;
    
    __STATUS: INT_BIT;
    
    __INF: INT_BIT;
    
    __SCORE: CHAR_BIT;
    __LEVEL: INT_BIT;
    
    #undef __PARA_LEN
    #undef __PARA_LOCATION
    
    #undef __STATUS
    
    #undef __INF
    
    #undef __SCORE
    #undef __LEVEL
};

const struct Stu_Metion
{
    Status (*newStudent)( const Information*,Student** );
    Status ( *setScore)( const Student* );
    Status ( *getScore )(const Student*,unsigned char* );
    Status ( *printLevel)( const Student* );
    Status ( *dropStu)( Student** );
}stu_metion=
{
    newStudent,
    setScore,
    getScore,
    printLevel,
    dropStu
};

struct Information
{
    const char* inf[6];
    Student* stu;
    
    const Stu_Metion const* metion;
    
}stu_inf=
{
    {"满分","优","良","好","合格","挂科"},
    NULL,
    &stu_metion
};

int main( void )
{
   
    const Stu_Metion* const metion=stu_inf.metion; 
    
     Student**const stu=&stu_inf.stu;
     
     unsigned char score;
     
     if (metion->newStudent(&stu_inf,stu))
     {
        puts("分配空间没有实现!");
        
        metion->dropStu(stu);
        
        exit(EXIT_FAILURE);
     }

    if (metion->setScore(*stu))
    {
        puts("成绩输入错误!");
        
        metion->dropStu(stu);
        
        exit(EXIT_FAILURE);
    }

 
    metion->getScore(*stu,&score); 

     printf("学生成绩已成功读取,为:%hhu\n",score);
     
     metion->printLevel(*stu);
     
     metion->dropStu(stu);
     
    return 0;
}

void nodeMal( void** p,size_t size )
{
    assert(p);
    
    *p=malloc(size);
    
    assert(*p);

    memset(*p,0,size);
}

void nodeFree( void** p )
{
    assert(p);
    
    free(*p);
    *p=NULL;
}

static void _Init_Student( size_t len,Student** stu,... )
{
    va_list ap;
    
    int**  p_list=NULL;
    int* p=NULL;
    
    unsigned count=8;
    
    size_t i;
    
    va_start(ap,stu);
    
    for (i=0;i!=len;++i)
        count+=va_arg(ap,int)/CHAR_BIT;
        
    nodeMal(( void** )stu,sizeof (Student)+count);
    
    IS_ERR(!*stu,__EFAULT);
  
    p_list=( int** )__PARA_LIST(*stu);
  
    nodeMal(( void** )p_list,(len+1)*sizeof (unsigned));
    
    IS_ERR(!*p_list,__EFAULT);
     
    va_start(ap,stu);

    count=0;
    for (p=*p_list;p!=*p_list+len;++p)
    {
        *p=count/CHAR_BIT;
        count+=va_arg(ap,int);
    }

 
    *p=count/CHAR_BIT;

    va_end(ap);
}

Status newStudent( const Information* stu_inf,Student** stu )
{
     IS_ERR(!stu,__EFAULT);

    _Init_Student(4,stu,INT_BIT,INT_BIT,CHAR_BIT,INT_BIT);
    
    IS_ERR(!*stu,__EFAULT);
    
    __PARA_DATA(*stu,1,Status)=__UN_INIT;
    __PARA_DATA(*stu,2,const Information*)=stu_inf; 

    return __OK;
}

Status setScore( const Student* stu )
{

    const Information* stu_inf=NULL;
    const Information t_inf;
     
    const size_t len=sizeof (t_inf.inf)/sizeof (*t_inf.inf);
    
    unsigned score;
    
    int c;
    
    IS_ERR(!stu,__EFAULT);
   
    puts("请输入学生成绩:");
         
    if (scanf("%u",&score)!=1||score>100)
    {
        
        while ((c=getchar())!=EOF&&c!='\n');
        
        __PARA_DATA(stu,1,Status)=__ERROR;
        
        return __ERROR;
     }
     
     while ((c=getchar())!=EOF&&c!='\n');

 stu_inf=__PARA_DATA(stu,2,Information*);
                 
     __PARA_DATA(stu,4,const char*)=(score>59?*(stu_inf->inf+10-(score/10)):*(stu_inf->inf+len-1));    
     __PARA_DATA(stu,3,unsigned char )=score;
         
     return __PARA_DATA(stu,1,Status)=__OK;
  
}

#define __IS_DATA_ERR( stu )    \
    do    \
    {    \
          IS_ERR(!(stu),__EFAULT);    \
        {    \
            const Status      __STU_COM=__PARA_DATA((stu),1,Status);    \
        \
            IS_ERR(__STU_COM,__STU_COM);    \
        }    \
    }while (0)

Status getScore( const Student* stu,unsigned char* score )
{
    __IS_DATA_ERR(stu);
      
    *score=__PARA_DATA(stu,3,unsigned char);
   
    return __OK;
}

Status printLevel( const Student* stu )
{
    __IS_DATA_ERR(stu);
    
    printf("评价等级为:%s\n",__PARA_DATA(stu,4,const char*));
    
    return __OK;
}

#undef __IS_DATA_ERR

Status dropStu( Student** stu )
{
    IS_ERR(!stu,__EFAULT);
    IS_ERR(!*stu,__EFAULT);
    
    {
        void** stu_list=( void* )__PARA_LIST(*stu);
    
        nodeFree(stu_list);
        nodeFree(( void** )stu);
    }
      
    return __OK;
}

2017-04-17-00-00更~
原来之前发现sizeof (Student)=0;也就是说匿名结构体成员sizeof检索不了,或者说是把分配的空间隐藏起来了,找了很久bug发现是因为分配空间问题从而对"越界部分"写入数据,结果因为系统数据更新修改该储存值而出问题了,这个是值得注意的,现在改好了,可以用了~

[此贴子已经被作者于2018-4-17 00:24编辑过]