7.3

#include <stdio.h>#include <stdlib.h>void Swap (int a,int b){    int max=-1;    if(b<a)    max=a;    if (a<b)        max=b;printf ("max=%d\n",max);}int main(){    int a,b;    printf("输入两个正整数：");    scanf ("%d %d",&a,&b);    Swap (a,b);    printf("a=%d,b=%d\n",a,b);    return 0;}

知识点：返回值的运用
心得体会：一定要确定要返回的值