c++字符串和整数的转换

#include<iostream>
using namespace std;
void fun1(char s[], const int a)//数字转换为字符，或者用库函数itoa()
{
int temp = a;
int i = 0;
while (temp)
{
s[i] = temp % 10 + '0';
temp = temp / 10;
i++;
}
s[i] = '\0';


}
void fun2(int &a, const char s[])//字符转换为数字；
{
char temp[10]{};
strcpy_s(temp, s);
int n = strlen(temp);
int sum = 0;
for (int i = 0; i < n; i++)
{
int jishu = 1;
int he = 0;
int k = i;
for (k = n - 1 - i; k>0; k--)
{
jishu = jishu * 10;
}
he = s[i] - '0';
he = he*jishu;
sum = sum + he;
}
a = sum;




}
int main()
{
int m = 12345;
char b[6]{};
char s[6] = "12345";
int e;
fun1(b, m);
cout << b << endl;//输出字符
fun2(e, s);
cout << e << endl;//输出数字
return 0;


}