Arithmetic operator +-x/%++/assignment operator=/comparison operator><=/logic operator!&&||
Table of contents
Fourth, the comparison operator
1. Brief introduction
Organize some knowledge developed in C++, so that you can consult and use it in time when you encounter similar problems later.
This section introduces the operators used to execute code operations, including arithmetic operator +-x/%++/assignment operator=/comparison operator><=/logical operator !&&|| and precautions. If there are deficiencies, welcome to point out, or if you have a better method, please leave a message.
2. Arithmetic operators
Function: used to process four operations
Arithmetic operators include the following symbols:
| operator | the term | example | result |
|---|---|---|---|
| + | plus sign | +3 | 3 |
| - | negative | -3 | -3 |
| + | add | 10 + 5 | 15 |
| - | reduce | 10 - 5 | 5 |
| * | take | 10 * 5 | 50 |
| / | remove | 10 / 5 | 2 |
| % | modulo (remainder) | 10 % 3 | 1 |
| ++ | Pre-increment | a=2; b=++a; | a=3; b=3; |
| ++ | post-increment | a=2; b=a++; | a=3; b=2; |
| – | pre-decrement | a=2; b=–a; | a=1; b=1; |
| – | post-decrement | a=2; b=a–; | a=1; b=2; |
1. + - x / Code:
Note: In the division operation, the divisor cannot be 0
#include <iostream>
using namespace std;
int main() {
int a1 = 10;
int b1 = 3;
cout << a1 + b1 << endl;
cout << a1 - b1 << endl;
cout << a1 * b1 << endl;
cout << a1 / b1 << endl; //两个整数相除结果依然是整数
int a2 = 10;
int b2 = 20;
cout << a2 / b2 << endl;
int a3 = 10;
int b3 = 0;
//cout << a3 / b3 << endl; //报错，除数不可以为0
//两个小数可以相除
double d1 = 0.5;
double d2 = 0.25;
cout << d1 / d2 << endl;
system("pause");
return 0;
}2. Modulo% code:
Note: 1) Only integer variables can perform modulo operations; 2) The divisor cannot be 0
#include <iostream>
using namespace std;
int main() {
int a1 = 10;
int b1 = 3;
cout << 10 % 3 << endl;
int a2 = 10;
int b2 = 20;
cout << a2 % b2 << endl;
int a3 = 10;
int b3 = 0;
//cout << a3 % b3 << endl; //取模运算时，除数也不能为0
//两个小数不可以取模
double d1 = 3.14;
double d2 = 1.1;
//cout << d1 % d2 << endl;
system("pause");
return 0;
}3. Auto-increment ++ code:
Note: The pre-increment first performs ++ on the variable, and then calculates the expression, and the post-increment is the opposite
#include <iostream>
using namespace std;
int main() {
//后置递增
int a = 10;
a++; //等价于a = a + 1
cout << a << endl; // 11
//前置递增
int b = 10;
++b;
cout << b << endl; // 11
//区别
//前置递增先对变量进行++，再计算表达式
int a2 = 10;
int b2 = ++a2 * 10;
cout << b2 << endl;
//后置递增先计算表达式，后对变量进行++
int a3 = 10;
int b3 = a3++ * 10;
cout << b3 << endl;
system("pause");
return 0;
}3. Assignment operator
Role: used to assign the value of an expression to a variable
Assignment operators include the following symbols:
| operator | the term | example | result |
|---|---|---|---|
| = | assignment | a=2; b=3; | a=2; b=3; |
| += | add equal to | a=0; a+=2; | a=2; |
| -= | minus equal to | a=5; a-=3; | a=2; |
| *= | multiply equal to | a=2; a*=2; | a=4; |
| /= | divide equal to | a=4; a/=2; | a=2; |
| %= | Modulus is equal to | a=3; a%2; | a=1; |
code:
#include <iostream>
using namespace std;
int main() {
//赋值运算符
// =
int a = 10;
a = 100;
cout << "a = " << a << endl;
// +=
a = 10;
a += 2; // a = a + 2;
cout << "a = " << a << endl;
// -=
a = 10;
a -= 2; // a = a - 2
cout << "a = " << a << endl;
// *=
a = 10;
a *= 2; // a = a * 2
cout << "a = " << a << endl;
// /=
a = 10;
a /= 2; // a = a / 2;
cout << "a = " << a << endl;
// %=
a = 10;
a %= 2; // a = a % 2;
cout << "a = " << a << endl;
system("pause");
return 0;
}Fourth, the comparison operator
Function: used to compare expressions and return a true or false value
Comparison operators have the following symbols:
| operator | the term | example | result |
|---|---|---|---|
| == | equal to | 4 == 3 | 0 |
| != | not equal to | 4 != 3 | 1 |
| < | less than | 4 < 3 | 0 |
| > | more than the | 4 > 3 | 1 |
| <= | less than or equal to | 4 <= 3 | 0 |
| >= | greater or equal to | 4 >= 1 | 1 |
code:
Tip: In the comparison operation of C and C++ languages, "true" is represented by the number "1", and "false" is represented by the number "0".
#include <iostream>
using namespace std;
int main() {
int a = 10;
int b = 20;
cout << (a == b) << endl; // 0
cout << (a != b) << endl; // 1
cout << (a > b) << endl; // 0
cout << (a < b) << endl; // 1
cout << (a >= b) << endl; // 0
cout << (a <= b) << endl; // 1
system("pause");
return 0;
}5. Logical operators
Function: used to return a true value or a false value according to the value of the expression
Logical operators have the following symbols:
| operator | the term | example | result |
|---|---|---|---|
| ! | No | !a | If a is false, !a is true; if a is true, !a is false. |
| && | and | a && b | The result is true if both a and b are true, otherwise false. |
| || | or | a || b | If either a or b is true, the result is true, and if both are false, the result is false. |
1. Logical NOT! Code:
Motto: True becomes false, false becomes true
#include <iostream>
using namespace std;
int main() {
int a = 10;
cout << !a << endl; // 0
cout << !!a << endl; // 1
system("pause");
return 0;
}2. Logical AND && Code:
Motto: The same truth is true, the rest are false
#include <iostream>
using namespace std;
int main() {
int a = 10;
int b = 10;
cout << (a && b) << endl;// 1
a = 10;
b = 0;
cout << (a && b) << endl;// 0
a = 0;
b = 0;
cout << (a && b) << endl;// 0
system("pause");
return 0;
}3. Logical OR || Code:
Motto: the same false is false, the rest are true
#include <iostream>
using namespace std;
int main() {
int a = 10;
int b = 10;
cout << (a || b) << endl;// 1
a = 10;
b = 0;
cout << (a || b) << endl;// 1
a = 0;
b = 0;
cout << (a || b) << endl;// 0
system("pause");
return 0;
}