用Xcode来写C++程序[3] Constants
以下是一些基本数据的含义:
75 // int
75u // unsigned int
75l // long
75ul // unsigned long
75lu // unsigned long 3.14159 // 3.14159
6.02e23 // 6.02 x 10^23
1.6e-19 // 1.6 x 10^-19
3.0 // 3.0 3.14159L // long double
6.02e23f // float 'z'// 单个字符
"How do you do?"// 字符串
一些符号的含义:
bool类型以及指针bool foo = true;
bool bar = false;
int* p = nullptr;
const变量
#include <iostream>
using namespace std;
const double pi = 3.14159;
const char newline = '\n';
int main ()
{
double r=5.0; // radius
double circle;
circle = 2 * pi * r;
cout << circle;
cout << newline;
宏定义:
#include <iostream>
using namespace std;
#define PI 3.14159
#define NEWLINE '\n'
int main ()
{
double r=5.0; // radius
double circle;
circle = 2 * PI * r;
cout << circle;
cout << NEWLINE;
}