C++ operators


An operator is a symbol that tells the compiler to perform a specific mathematical or logical operation. C++ has a rich set of built-in operators and provides the following types of operators:

  • Arithmetic operators

  • Relational operators

  • Logical operators

  • Bitwise operators

  • ##Assignment operators

  • Miscellaneous operators

This chapter will introduce arithmetic operators, relational operators, logical operators, bitwise operators, assignment operators and other operators one by one.

Arithmetic operators

The following table shows the arithmetic operators supported by C++.

Assume that the value of variable A is 10 and the value of variable B is 20, then:

OperatorDescriptionExample+Add the two operandsA + B will get 30- Subtracting the second operand from the first operand A - B will give -10 *Multiply the two operandsA * B will get 200##/##%modulo operator, the remainder after integer division B % A will get 0++Increment operator, integer value increased by 1A++ will get 11-- Decrement operator, decrement the integer value by 1A-- will get 9

Examples

See the examples below to learn about the arithmetic operators available in C++.

Copy and paste the following C++ program into the test.cpp file, compile and run the program. 

#include <iostream>
using namespace std;
 
main()
{
   int a = 21;
   int b = 10;
   int c ;
 
   c = a + b;
   cout << "Line 1 - c 的值是 " << c << endl ;
   c = a - b;
   cout << "Line 2 - c 的值是 " << c << endl ;
   c = a * b;
   cout << "Line 3 - c 的值是 " << c << endl ;
   c = a / b;
   cout << "Line 4 - c 的值是 " << c << endl ;
   c = a % b;
   cout << "Line 5 - c 的值是 " << c << endl ;
   c = a++; 
   cout << "Line 6 - c 的值是 " << c << endl ;
   c = a--; 
   cout << "Line 7 - c 的值是 " << c << endl ;
   return 0;
}

When the above code is compiled and executed, it produces the following results: 

Line 1 - c 的值是 31
Line 2 - c 的值是 11
Line 3 - c 的值是 210
Line 4 - c 的值是 2
Line 5 - c 的值是 1
Line 6 - c 的值是 21
Line 7 - c 的值是 22

Relational operators

The following table shows the relational operators supported by C++.

Assume that the value of variable A is 10 and the value of variable B is 20, then:

Divide the numerator by the denominatorB / A will get 2
OperatorDescription Example
== Check whether the values ​​of the two operands are equal. If they are equal, the condition is true. (A == B) is not true.
!= Checks whether the values ​​of the two operands are equal. If they are not equal, the condition is true. (A != B) is true.
>Checks whether the value of the left operand is greater than the value of the right operand, if so, the condition is true. (A > B) is not true.
<Checks whether the value of the left operand is less than the value of the right operand, if so the condition is true. (A < B) is true.
>=Checks whether the value of the left operand is greater than or equal to the value of the right operand, if so the condition is true. (A >= B) is not true.
<=Checks whether the value of the left operand is less than or equal to the value of the right operand, if so the condition is true. (A <= B) is true.

Examples

See the examples below to learn about the relational operators available in C++.

Copy and paste the following C++ program into the test.cpp file, compile and run the program. 

#include <iostream>
using namespace std;

main()
{
   int a = 21;
   int b = 10;
   int c ;

   if( a == b )
   {
      cout << "Line 1 - a 等于 b" << endl ;
   }
   else
   {
      cout << "Line 1 - a 不等于 b" << endl ;
   }
   if ( a < b )
   {
      cout << "Line 2 - a 小于 b" << endl ;
   }
   else
   {
      cout << "Line 2 - a 不小于 b" << endl ;
   }
   if ( a > b )
   {
      cout << "Line 3 - a 大于 b" << endl ;
   }
   else
   {
      cout << "Line 3 - a 不大于 b" << endl ;
   }
   /* 改变 a 和 b 的值 */
   a = 5;
   b = 20;
   if ( a <= b )
   {
      cout << "Line 4 - a 小于或等于 b" << endl ;
   }
   if ( b >= a )
   {
      cout << "Line 5 - b 大于或等于 a" << endl ;
   }
   return 0;
}

When the above code is compiled and executed, it produces the following results: 

Line 1 - a 不等于 b
Line 2 - a 不小于 b
Line 3 - a 大于 b
Line 4 - a 小于或等于 b
Line 5 - b 大于或等于 a

Logical operators

The following table shows the relational logical operators supported by C++ .

Assume that the value of variable A is 1 and the value of variable B is 0, then:

OperatorDescription Example
&& is called the logical AND operator. The condition is true if both operands are non-zero. (A && B) is false.
|| is called the logical OR operator. The condition is true if either of the two operands is non-zero. (A || B) is true.
! is called the logical NOT operator. Used to reverse the logical state of the operand. The logical NOT operator will make the condition false if it is true. !(A && B) is true.

Examples

See the examples below to learn about the logical operators available in C++.

Copy and paste the following C++ program into the test.cpp file, compile and run the program. 

#include <iostream>
using namespace std;

main()
{
   int a = 5;
   int b = 20;
   int c ;

   if ( a && b )
   {
      cout << "Line 1 - 条件为真"<< endl ;
   }
   if ( a || b )
   {
      cout << "Line 2 - 条件为真"<< endl ;
   }
   /* 改变 a 和 b 的值 */
   a = 0;
   b = 10;
   if ( a && b )
   {
      cout << "Line 3 - 条件为真"<< endl ;
   }
   else
   {
      cout << "Line 4 - 条件不为真"<< endl ;
   }
   if ( !(a && b) )
   {
      cout << "Line 5 - 条件为真"<< endl ;
   }
   return 0;
}

When the above code is compiled and executed, it produces the following results: 

Line 1 - 条件为真
Line 2 - 条件为真
Line 4 - 条件不为真
Line 5 - 条件为真

Bit operators

Bit operators act on bits and are executed bit by bit operate. The truth table for &, | and ^ is as follows:

pqp & qp | qp ^ q
0000 0
01011
11110
10011
## Suppose if A = 60, and B = 13, now represented in binary format, they look like this:

A = 0011 1100

B = 0000 1101

---------- -------

A&B = 0000 1100

A|B = 0011 1101

A^B = 0011 0001

~A = 1100 0011

The following table shows the bitwise operators supported by C++. Assume that the value of variable A is 60 and the value of variable B is 13, then:

OperatorDescriptionExample&The binary AND operator copies one bit to the result if both operands are present at the same time. (A & B) will get 12, which is 0000 1100|If present in any operand, binary OR operation character is copied into the result. (A | B) will get 61, which is 0011 1101^ if present in one of the operands but not both The binary XOR operator copies one of the two operands into the result. (A ^ B) will get 49, which is 0011 0001~The two's complement operator is a unary operator with " Flip" bit effect. (~A ) will get -61, which is 1100 0011, 2's complement, signed binary number. <<Binary left shift operator. The value of the left operand is shifted left by the number of bits specified by the right operand. A << 2 will get 240, which is 1111 0000##>>

Examples

See the examples below to learn about the bitwise operators available in C++.

Copy and paste the following C++ program into the test.cpp file, compile and run the program. 

#include <iostream>
using namespace std;

main()
{
   unsigned int a = 60;	  // 60 = 0011 1100  
   unsigned int b = 13;	  // 13 = 0000 1101
   int c = 0;           

   c = a & b;             // 12 = 0000 1100
   cout << "Line 1 - c 的值是 " << c << endl ;

   c = a | b;             // 61 = 0011 1101
   cout << "Line 2 - c 的值是 " << c << endl ;

   c = a ^ b;             // 49 = 0011 0001
   cout << "Line 3 - c 的值是 " << c << endl ;

   c = ~a;                // -61 = 1100 0011
   cout << "Line 4 - c 的值是 " << c << endl ;

   c = a << 2;            // 240 = 1111 0000
   cout << "Line 5 - c 的值是 " << c << endl ;

   c = a >> 2;            // 15 = 0000 1111
   cout << "Line 6 - c 的值是 " << c << endl ;

   return 0;
}

When the above code is compiled and executed, it produces the following results: 

Line 1 - c 的值是 12
Line 2 - c 的值是 61
Line 3 - c 的值是 49
Line 4 - c 的值是 -61
Line 5 - c 的值是 240
Line 6 - c 的值是 15

Assignment Operators

The following table lists the assignment operators supported by C++ :

Binary right shift operator. The value of the left operand is shifted to the right by the number of bits specified by the right operand. A >> 2 will get 15, which is 0000 1111
##/= division and assignment operator, which assigns the result of dividing the left operand by the right operand For the left operand C /= A, it is equivalent to C = C / A%=. Find two modulus and assignment operators. The modulus of the operand is assigned to the left operand C %= A which is equivalent to C = C % A<<=left shift And the assignment operator C <<= 2 is equivalent to C = C << 2##>>=&=^=##|=Bitwise OR and assignment operatorC |= 2 is equivalent to C = C | 2

Examples

See the examples below to learn about the assignment operators available in C++.

Copy and paste the following C++ program into the test.cpp file, compile and run the program. 

#include <iostream>
using namespace std;

main()
{
   int a = 21;
   int c ;

   c =  a;
   cout << "Line 1 - =  运算符实例，c 的值 = : " <<c<< endl ;

   c +=  a;
   cout << "Line 2 - += 运算符实例，c 的值 = : " <<c<< endl ;

   c -=  a;
   cout << "Line 3 - -= 运算符实例，c 的值 = : " <<c<< endl ;

   c *=  a;
   cout << "Line 4 - *= 运算符实例，c 的值 = : " <<c<< endl ;

   c /=  a;
   cout << "Line 5 - /= 运算符实例，c 的值 = : " <<c<< endl ;

   c  = 200;
   c %=  a;
   cout << "Line 6 - %= 运算符实例，c 的值 = : " <<c<< endl ;

   c <<=  2;
   cout << "Line 7 - <<= 运算符实例，c 的值 = : " <<c<< endl ;

   c >>=  2;
   cout << "Line 8 - >>= 运算符实例，c 的值 = : " <<c<< endl ;

   c &=  2;
   cout << "Line 9 - &= 运算符实例，c 的值 = : " <<c<< endl ;

   c ^=  2;
   cout << "Line 10 - ^= 运算符实例，c 的值 = : " <<c<< endl ;

   c |=  2;
   cout << "Line 11 - |= 运算符实例，c 的值 = : " <<c<< endl ;

   return 0;
}

When the above code is compiled and executed, it produces the following results: 

Line 1 - =  运算符实例，c 的值 = 21
Line 2 - += 运算符实例，c 的值 = 42
Line 3 - -= 运算符实例，c 的值 = 21
Line 4 - *= 运算符实例，c 的值 = 441
Line 5 - /= 运算符实例，c 的值 = 21
Line 6 - %= 运算符实例，c 的值 = 11
Line 7 - <<= 运算符实例，c 的值 = 44
Line 8 - >>= 运算符实例，c 的值 = 11
Line 9 - &= 运算符实例，c 的值 = 2
Line 10 - ^= 运算符实例，c 的值 = 0
Line 11 - |= 运算符实例，c 的值 = 2

Miscellaneous operators

The following table lists some other important ones supported by C++ operator.

OperatorDescriptionInstance
=Simple assignment operator, assigns the value of the right operand to the left operandC = A + B will assign the value of A + B to C
+=Addition and assignment operator, assigns the result of adding the right operand to the left operand to the left operandC += A is equivalent to C = C + A
-=Subtraction and assignment operator, assigns the result of subtracting the right operand from the left operand to the left operand C -= A is equivalent to C = C - A
*=The multiplication and assignment operator assigns the result of multiplying the right operand by the left operand to the left operandC *= A is equivalent to C = C * A
Right shift and assignment operator C >>= 2 is equivalent to C = C >> 2
Press Bitwise AND and assignment operatorC &= 2 is equivalent to C = C & 2
Bitwise XOR and assignment operator The symbol C ^= 2 is equivalent to C = C ^ 2
OperatorDescription
sizeofsizeof operator returns the size of the variable . For example, sizeof(a) returns 4, where a is an integer.
Condition ? X : YConditional operator. The value is X if Condition is true ? : otherwise the value is Y.
,The comma operator performs a series of operations sequentially. The value of the entire comma expression is the value of the last expression in the comma-separated list.
. (dot) and -> (arrow) Member operators are used to refer to members of classes, structures, and unions.
CastThe cast operator converts one data type to another data type. For example, int(2.2000) returns 2.
&Pointer operator & returns the address of the variable. For example &a; will give the actual address of the variable.
*Pointer operator * points to a variable. For example, *var; will point to the variable var.

Operator precedence in C++

The precedence of an operator determines the combination of terms in an expression. This affects how an expression is evaluated. Some operators have higher precedence than others, for example, multiplication and division operators have higher precedence than addition and subtraction operators.

For example x = 7 + 3 * 2, here, x is assigned the value 13 instead of 20, because the operator * has a higher priority than +, so the multiplication 3*2 is calculated first, and then Plus 7 more.

The following table lists each operator according to operator priority from high to low. Operators with higher priority appear at the top of the table, and operators with lower priority appear at the bottom of the table. under. In an expression, operators with higher precedence are evaluated first.

Category Operator Associativity
Suffix () [] -> . ++ - - From left to right
One yuan + - ! ~ ++ - - (type)* & sizeof From right to left
Multiplication and division * / % From left to right
Addition and subtraction + - From left to right
Shift << >> From left to right
Relationship < <= > >= From left to right
Equal == != From left to right
Bit AND AND & From left to right
Bit XOR XOR ^ From left to right
Bit OR | From left to right
Logic AND && from left to right
logical OR || from left To the right
Condition ?: From right to left
Assignment = += -= *= /= %=>>= <<= &= ^= |= From right to left
comma , From left to right

Example

Please see the following example to learn about C++ The precedence of the operator.

Copy and paste the following C++ program into the test.cpp file, compile and run the program.

Compare the difference between parentheses and without parentheses, which will produce different results. Because (), /, *, and + have different precedence, the higher precedence operator will be evaluated first. 

#include <iostream>
using namespace std;
 
main()
{
   int a = 20;
   int b = 10;
   int c = 15;
   int d = 5;
   int e;
 
   e = (a + b) * c / d;      // ( 30 * 15 ) / 5
   cout << "(a + b) * c / d 的值是 " << e << endl ;

   e = ((a + b) * c) / d;    // (30 * 15 ) / 5
   cout << "((a + b) * c) / d 的值是 " << e << endl ;

   e = (a + b) * (c / d);   // (30) * (15/5)
   cout << "(a + b) * (c / d) 的值是 " << e << endl ;

   e = a + (b * c) / d;     //  20 + (150/5)
   cout << "a + (b * c) / d 的值是 " << e << endl ;
  
   return 0;
}

When the above code is compiled and executed, it produces the following results: 

(a + b) * c / d 的值是 90
((a + b) * c) / d 的值是 90
(a + b) * (c / d) 的值是 90
a + (b * c) / d 的值是 50