C语言例题 求排错

#include "stdio.h"
main()
{
void s(char [],char []); //别再函数里定义函数
char s1[20]="abc",s2[5]="def";
s(s1,s2);
printf{"%s\n",s1}; //是小()不是{}
}
void s(char s1[],char s2[])
{
int i,j;
i=j=0;
while(s1[i]!='\0')
i++;
while(s2[j]!='\0')
s1[i++]=s2[j++];
s1[i]='\0';
}

改：
#include "stdio.h"
void s(char [],char []);
main()
{
char s1[20]="abc",s2[5]="def";
s(s1,s2);
printf("%s\n",s1);
}
void s(char s1[],char s2[])
{
int i,j;
i=j=0;
while(s1[i]!='\0')
i++;
while(s2[j]!='\0')
s1[i++]=s2[j++];
s1[i]='\0';
}

你不介意把函数声明放到main外面去吧。