今天在做练习题时遇到的奇怪问题，加了一些输出还是没有想明白问题在哪，主要问题是代码在何时更改了s1字符串的，因为我全程没有对s1做过任何更改。

include <stdio.h>

include <string.h>

void expand(char s1[], char s2[]){
int i,j,k;

k=strlen(s2);
for(i=1;s1[i+1]!='\0';i++){
	if(s1[i]=='-'){
		if((s1[i+1]<='z'&&s1[i+1]>='a'&&s1[i-1]<='z'&&s1[i-1]>='a'&&s1[i+1]>=s1[i-1])||(s1[i+1]<='Z'&&s1[i+1]>='A'&&s1[i-1]<='Z'&&s1[i-1]>='A'&&s1[i+1]>=s1[i-1])||(s1[i+1]<='9'&&s1[i+1]>='0'&&s1[i-1]<='9'&&s1[i-1]>='0'&&s1[i+1]>=s1[i-1]))
		{
			for(j=0;j<(s1[i+1]-s1[i-1])&&printf("%s",s1);j++){
				s2[k+j]=s1[i-1]+j;
				printf("%3d  %s  %d\n",j,s1,s1[i-1]);
			}	
    	s2[k+j]='\0';
		}
	}
}

}
int main(){
char s1[]="a-z";
char s2[]="sdbver";
expand(s1,s2);
printf("%s",s2);
}

输出如图!