深入C++实现函数itoa()的分析
// TestInheritance.cpp : 定义控制台应用程序的入口点。
//
#include "stdafx.h"
#include
#include
#include
using namespace std;
int myItoa(int data, char* p, int num)
{
if (p == NULL)
{
return -1;
}
if (data < 0)
{
*p++ = '-';
data = 0 - data;
}
int temp = 0;
int flag = 0; //标志位 0-不存储 1-存储
if (num == 10)
{//十进制
for (int i = 0; i < 10; i++)
{
temp = static_cast
if (temp != 0) //去掉最前面的0
{
flag = 1;//将标志位变为1，可以存储
}
if (flag != 0)
{
*p++ = temp + '0'; //变成字符
data = data % static_cast
}
}
}
else if (num == 2)
{//二进制
for (int i = 0; i < 32; i++)
{
temp = static_cast
if (temp != 0)
{
flag = 1;
}
if (flag != 0)
{
*p++ = temp + '0';
data = data % static_cast
}
}
}
else if (num == 16)
{//十六进制
for (int i = 0; i < 8; i++)
{
temp = static_cast
if (temp != 0)
{
flag = 1;
}
if (flag != 0)
{
if (temp >= 0 && temp <= 9)
{
*p++ = temp + '0';
}
else if (temp >= 10 && temp <= 15)
{
*p++ = temp - 10 + 'A';
}
data = data % static_cast
}
}
}
else if (num == 8)
{//八进制
for (int i = 0; i < 16; i++)
{
temp = static_cast
if (temp != 0)
{
flag = 1;
}
if (flag != 0)
{
*p++ = temp + '0';
data = data % static_cast
}
}
}
}
int _tmain(int argc, _TCHAR* argv[])
{
int i = 100;
char a[32] ={0};
char b[32] ={0};
char c[32] ={0};
char d[32] ={0};
cout << i << "的八进制表示为: ";
myItoa(i, a, 8);
cout << a << endl;
cout << i << "的十进制表示为: ";
myItoa(i, b, 10);
cout << b << endl;
cout << i << "的二进制表示为: ";
myItoa(i, c, 2);
cout << c << endl;
cout << i << "的十六进制表示为: ";
myItoa(i, d, 16);
cout << d << endl;
return 0;
}