The basis of C language grammar -- function nesting, Fibonacci sum of recursive applet and factorial

long jiecheng(int num){
    
	long result=1,i;
	for(i=1;i<=num;i++){
    
		result*=i;
	}
	return result;
}

long pingfang(int a){
    
	return jiecheng(a*a);
}

int main(int argc, char *argv[]) {
    
	// s=2 2! + 3 3! + 4 4!
	int i;
	long res=0;
	for(i=2;i<=4;i++){
    
		res+=pingfang(i);
	}
	
	printf("%1d",res);
	
	
	return 0;
}
//*********************************************************

// 4 Recursive factorial of  4！= 1*2*3*4 = 4*3*2*1
long jiecheng(int n){
    
	long result;
	if(n<=1){
    
		result=1;
	}else{
    
		result=n*jiecheng(n-1); // 
	}
	return result;
}

int main(int argc, char *argv[]) {
    
	printf("%d",jiecheng(4));
	
	
	return 0;
}
//*********************************************************

//  Napoch 12 and  1 1 2 3 5 8 13 21 34
int f(int n){
    
	if(n==1 || n==2){
    
		return 1;
	}else{
    
		return f(n-1)+f(n-2); // 
	}
}

int main(int argc, char *argv[]) {
    
	int sum=0,i;
	for(i=1;i<=12;i++){
    
		sum += f(i);
	}
	printf("%d",sum);
	
	
	return 0;
}