字符串拷贝

#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#include<string.h>
int main(void)
{
    char *s1;
    s1=(char*)malloc(20*sizeof(char));
    printf("Input a string:\n");
    scanf("%s",s1);
    printf("Input is:%s\n",s1);
    char* s2;
    s2=(char*)malloc((strlen(s1)+1)*sizeof(char));
    for(int i=0;i<strlen(s1);i++)
        s2[i]=toupper(s1[i]);
        s2[strlen(s1)]='\0';
    printf("TOUPPER is:%s\n",s2);
    return 0;
}