善用常量数组往往能简化代码。定义常量数组时无须指明大小，编译器会计算。
下面是两道例题

$WERTYU$（$UVa10082$）

<code c>
#include<stdio.h>
char s[] = "`1234567890-=QWERTYUIOP[]\\ASDFGHJKL;'ZXCVBNM,./";
int main(){
    int i, c;
    while((c = getchar()) != EOF){
        for (i=1; s[i] && s[i]!=c;i++);
        if(s[i]) putchar(s[i-1]);
        else putchar(c);
    }
    return 0;
}
</code>
回文词（$UVa401$）

输入一个字符串，判断它是否为回文串以及镜像串。输入字符串保证不含数字0。（使用常量数组）
<code c>
#include<stdio.h>
#include<string.h>
#include<ctype.h>
const char* rev = "A   3  HIL JM O   2TUVWXY51SE Z  8 ";
const char* msg[] = {"not a palindrome", "a regular palindrome", "a mirrored string", "a mirrored palindrome"};

char r(char ch) {
  if(isalpha(ch)) return rev[ch - 'A'];
  return rev[ch - '0' + 25];
}

int main() {
  char s[30];
  while(scanf("%s", s) == 1) {
    int len = strlen(s);
    int p = 1, m = 1;
    for(int i = 0; i < (len+1)/2; i++) {
      if(s[i] != s[len-1-i]) p = 0;
      if(r(s[i]) != s[len-1-i]) m = 0;
    }
    printf("%s -- is %s.\n\n", s, msg[m*2+p]);
  }
  return 0;
}
</code>