C菜鸡抄代码

今天抄了些代码，时间又晚了这么多

How to check the type of n?

#include"stdio.h"
#include"string.h"
#include"math.h"
void  strlen1(char* p);
void strTonum();
int main()
{
	char str1[100] = "ABCD";
	char str2[] = "EFG";
	char str3[20];
	//*str1 = scanf("%s", str1);
	//*str2 = scanf("%s", str2);

	char* strcat(char* str1, char* str2);
	printf("The string after the connection is %s\n", strcat(str1, str2));

	scanf("%s", str3);
	strlen1(str3);

 //   int  a=0;
	//printf("谁的瓜最多？（1.你的  2.还是你的):");
	//scanf("%d", &a);
	//if (a == 1)
	//	printf("卖你的瓜可以供疆整个夏天");
	//if (a == 2)
	//	printf("你是西瓜批发商！");
	 strTonum();
	while (1);
	return 0;
}
char* strcat(char* str1, char* str2)
{
	char* p, * q;
	p = str1;
	while (*p != '\0')
	{
		p++;
	}
	q = str2;
	while (*q != '\0')
	{
		*p = *q;
		p++;
		q++;
	}
	*p = '\0';
	return str1;
}
void  strlen1(char* p)
{
	int length = 0;
	while (*p != '\0')
	{
		length++;
		p++;
	}
	printf("The length of string is %d\n", length);
}
void strTonum()
{
	char s[20];
	printf("Please input a string which is not over 9:");
	scanf("%s",s);
	int len = 0;
	int i, k, n=0;
	len = strlen(s);
	for (i = 0; i < len; i++)
	{
		k = s[i] - '0';
		n = n * 10 + k;
	}
	printf("The string turned into %d", n);
	if (int(pow(n, 0.5)) == pow(n, 0.5))   // check the turnning is succeed or not?
		printf("The type of n is number");

}

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