河北大学程序设计训练营-day01

C++入门

第一步C++环境安装

安装DEVC++做演示

其他开发工具推荐: CodeBlocks、vscode、SublimeText

第一个==hello world==程序

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#include<iostream>

using namespace std;

int main(){

	cout << "hello world !" << endl;
}

基本语法程序

C++的基本类型和C语言无异

数值类型
  • 整型: (短整型)short 、（整型)int 、（长整型) long
  • 浮点类型: (单精度类型)float (双精度类型) double

字符类型:

  • 字符类型 : char
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#include<iostream>
using namespace std;
int main()
{
	//数字型
	short short_num = 99;
	int num = 999;
	long long_num = 9999;
	cout << "short_num = " << short_num << endl;
	cout << "long_num = " << long_num << endl;
	cout << "num = " << num << endl;
	cout << "next::" << endl;
	
	//字符型
	char ch;
	cin >> ch;
	cout << "ch = " << ch;

	//bool型
	bool flag = true;
	cout << "next::" << endl;
	cout << flag << endl;
	cout << false << endl;

	//const修饰的作用： "常量"
	const int i = 1;
	cout << i << endl;
	i = 100;
    
    for(int j=0; j< 10; ++j){
        cout << j;
    }
    if(1==1){
        cout << "hello world" <<endl;
    }
    
}

第一个测试程序

不再讲解

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#include<iostream>
using namespace std;
int main(){
    int a,b;
    cin >> a;
    cin >> b;
    cout << a+b;
}

第二题:

接收空格作为字符串的函数：cin.getline(s,100)

把字符串转换为整数:**A = A * 10 + new_number**

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#include<iostream>
using namespace std;
//123 456
//1   1*10 + 2  (1*10+2) * 10 +3  A = A * 10 + new


int main(){
	char s[100];
	bool flagA = true , flagB =true;
	int A = 0 , B = 0;
	
	cin.getline(s,100);
	int i;
	for( i=0 ; s[i]!=' ';++i);
	
	for( int j=0 ; j< i ;++j ){
		if(s[j] >='0' && s[j] <='9'){
			A = A * 10 + (s[j]-'0');
		} else{
			flagA = false; 
			break;
		}
	} 
	if(A ==0 || A >1000) flagA = false;
	
	for( int j=i+1 ; s[j]!='\0' ;++j ){
		if(s[j] >='0' && s[j] <='9'){
			B = B * 10 + (s[j]-'0');
		} else{
			flagB = false; 
			break;
		}
	} 
	if(B ==0 || B >1000) flagB = false;
	
	if(flagA){
		if(flagB){
			printf("%d + %d = %d",A,B,A+B);
		}else{
			printf("%d + ? = ?",A);
		}
	} else{
		if(flagB){
			printf("? + %d = ?",B);
		}else{
			printf("? + ? = ?");
		}
	}
	
}