C++入门基础

C++

C++ characteristics

• vector
• list, forward_list(singly-linked list), …
• map, unordered_map(hash table), …
• set, multi_set, …
• string
• thread
• memory management

C++

• compilation + linking
• OOP
• safe programming
• superset of C
• case sensitive

1 Hello world! print

#include<iostream.h> // header file: input and output stream
int main() // main function, machine's function
{
	cout << "Hello World!\n"; // not c++ output: statement cout << is included in #include<iostream.h>
    						// cout = console out, cout is an object for output to screen, << is operator
    						// "Hello World!\n" is operands
	return 0; // output of machine (main), return 0 means function success, can be other integer
    		  // this line optional
}

2 Variables

#include<iostream.h>
int main() // main function
{
	int a; // declaration
	a = 5; // initialization
	int b = a; // get the value of b
	a = 4; // another valur of a assigned
	cout << a; // output a
	cout << "\n"; // new line
	cout << b; // output b
	cout << "\n";
	return 0;
}

3 Better output

#include<iostream.h>
int main() // main function
{
	int a; // declaration
	a = 5; // initialization
	int b = a; // get the value of b
	a = 4; // another valur of a assigned
	cout << "a = " << a << "\n" << "b = " << b << endl; // output a and b, need only one cout, 
    													//endl = end line = "\n", not like c
    													// don't need %d to represent number
	return 0;
}

4 input

#include<iostream.h>
int main() // main function
{
	int a; // declaration
	cin >> a; // console in, 45 is the input of a 
	cout << "a = " << a << endl; // console out
	return 0;
}

5 functions used in Library

#include<iostream.h>
#include<cmath>
int main() // main function
{
	cout << pow(10, 2) << endl;
	return 0;
}

#include<iostream.h>
#include<cmath>
int main() // main function
{
	int base, exponent;
	cout << "What is the base?: ";
	cin >> base;
	cout << "What is the exponent?: ";
	cin >> exponent;
	cout << pow(base, exponent) << endl;
	return 0;
}

#include<iostream.h>
#include<cmath>
int main() // main function
{
	int base, exponent;
	cout << "What is the base?: ";
	cin >> base;
	cout << "What is the exponent?: ";
	cin >> exponent;
	double power = pow(base, exponent); // if use the value returned in function
	cout << power << endl;
	return 0;
}

6 creating custom functions

#include<iostream.h>

double power(double base, int exponent) // declaring and defining
{
	double result = 1;
	for(int i = 0; i < exponent; i++)
	{
		result = result * base;
	}
	return result;
}

int main() // main function
{
	int base, exponent;
	cout << "What is the base?: ";
	cin >> base;
	cout << "What is the exponent?: ";
	cin >> exponent;
	double my_power = power(base, exponent); // if use the value returned in function
	cout << my_power << endl;
	return 0;
}

标签：function,exponent,入门,int,基础,C++,base,main,cout
来源： https://blog.csdn.net/weixin_43012796/article/details/111145635