#include<stdio.h>
#define N5
 main()
  {        int num[N]={0},i=0,k=0;
          float score[N]={0.0};
         
          printf("input numbers and scores:\n");
          for(i=0;i<N;i++)
                  printf("%8d",num[i]);
          printf("\n");
         
          for(i=0;i<N;i++)
                  printf("%8d",score[i]);
          printf("\n");
         
          k=0;
          for(i=1;i<N;i++)
              if(score[k]<score[i]) k=i;
              
          printf("number=%d,score=%.2f\n",num[k],score[k]);
 
  }  
 

问题在于N这个地方，还有编辑器的提示信息如下。
A:\C语言编程练习\字符串3.c    In function 'main':
4    14    A:\C语言编程练习\字符串3.c    [Error] 'N' undeclared (first use in this function)
4    14    A:\C语言编程练习\字符串3.c    [Note] each undeclared identifier is reported only once for each function it appears in
我使用的是DEV C++5.9.2

#include<stdio.h>
#define N 5 //这里少了一个空格
main()
  {        int num[N]={0},i=0,k=0;
          float score[N]={0.0};
         
          printf("input numbers and scores:\n");
          for(i=0;i<N;i++)
                  printf("%8d",num[i]);
          printf("\n");
         
          for(i=0;i<N;i++)
                  printf("%8d",score[i]);
          printf("\n");
         
          k=0;
          for(i=1;i<N;i++)
              if(score[k]<score[i]) k=i;
              
          printf("number=%d,score=%.2f\n",num[k],score[k]);
 
  }

#define N5
//#define N 5

要把N和5分开写

如果合在一起写，编译器就把N5看成一个变量了~