使用函数完成的几个C语言例题

#include<stdio.h>
int main(){
    int max(int a,int b);
    int a=19,b=34;
    int m=max(a,b);
    printf("m=%d",m);
    return 0; 
} 
int max(int a,int b){
    int c;
    if(a>b)c=a;
    else c=b;
    return c;
}

#include<stdio.h>
int main(){
    int Fun1(double);
    double x;
    scanf("%lf",&x);
    double y;
    y=Fun1(x);;
    printf("%lf",y);
    return 0;
}
int Fun1(double x){
    double c;
    if(x>=10)c=2*x;
    else
    if(x<1)c=x;
    else c=2*x-1;
    return c;
}