习题4.1

(1)   

#include <stdio.h>#include <stdlib.h>int main(){    char c1='a',c2='b',c3='c';    printf("a%cb%cc%c\n",c1,c2,c3);    return 0;}

结果：aabbcc

(2)
#include <stdio.h>#include <stdlib.h>int main(){    int a=12,b=15;    printf("a=%d%%,b=%d%%\n",a,b);    return 0;}
结果：a=12%,b=12%
(3)
#include <stdio.h>#include <stdlib.h>int main(){    int a,b;    scanf("%2d*2s%2d",&a,&b);    printf("%d,%d\n",a,b);    return 0;}
结果：12,8