Tips and precautions for learning operator precedence in Go language

Tips and precautions for mastering the operator priority of Go language

Go language is a concise and efficient programming language with a wealth of operators used to implement various calculations and logical operations. When writing code, using operator precedence correctly can avoid errors and improve the readability and maintainability of your code. This article will introduce some tips and considerations about operator precedence in Go language, and provide specific code examples.

1. Understand the priority table of Go language operators
   The operators of Go language are arranged from high to low in priority. The specific priorities are as follows:

• Unary operators: ,--, ,-,!,^,*,&
• Multiplication operators: *,/,%
• Addition operators: ,-
• Shift operators: >
• Relational operators: , >=, ==, !=
• Bit operators: &, ^, |
• Logical operators: &&, ||
• Assignment operators: =, =, -=, *=, /=, % =, >=, &=, ^=, |=
• Comma operator:,

2. Use parentheses to change the operator Priority
   Sometimes we want the calculation order of an expression to be different from the default priority of the operator. We can use parentheses to change the priority. For example:

a := 2 + 3 * 4  // 结果为14
b := (2 + 3) * 4  // 结果为20

In the first expression, since the multiplication operator has a higher priority than the addition operator, 3 * 4 is calculated first, then 2 is added, and the final result is 14. In the second expression, the use of parentheses changes the priority of the expression. The addition expression in the parentheses is calculated first, and then multiplied by 4. The final result is 20.

3. Ensure that the operand type of the operator meets the requirements
   Each operator has its own operand type requirements. Using operands that do not meet the requirements will cause compilation errors. For example:

a := 5 / 2  // 除法运算符的操作数只能是整数类型，结果为2
b := 5.0 / 2  // 正确的写法，结果为2.5

In the first expression, a compilation error occurs because the operands of the division operator are required to be of integer type. In the second expression, changing one of the operands to a floating point number type will result in the correct result of 2.5.

4. Keep in mind the associativity of operators
   The associativity of operators refers to the order of calculation when the same operator appears multiple times without using parentheses. For example:

a := 2 * 3 / 4  // 结果为1
b := 2 / 3 * 4  // 结果为0

In the first expression, 2 * 3 is calculated first, and then divided by 4, the final result is 1. In the second expression, since the precedence of multiplication and division is the same and the associativity is from left to right, 2 / 3 is calculated first, and then multiplied by 4, and the final result is 0.

5. Note the result of integer division
   In the Go language, the result of division between integers is also an integer. For integer division, if the dividend is not divisible, the result is rounded down. For example:

a := 5 / 2  // 结果为2

In the above code, since 5 is not divisible by 2, the result of integer division will be rounded down, and the final result will be 2.

To sum up, mastering the skills and precautions of Go language operator priority is an important part of writing high-quality code. Reasonable use of parentheses to change the default priority of operators, ensuring that the operand types meet the requirements, keeping in mind the associativity of operators and paying attention to the results of integer division are all things we need to pay attention to when using operators. By mastering these tips and considerations, we can write more accurate and efficient code.

Reference code example:

package main

import "fmt"

func main() {
  a := 2 + 3 * 4
  b := (2 + 3) * 4
  c := 5 / 2
  d := 2 * 3 / 4

  fmt.Println(a)  // 输出14
  fmt.Println(b)  // 输出20
  fmt.Println(c)  // 输出2
  fmt.Println(d)  // 输出1
}

In the above code, we used various techniques and precautions mentioned above to verify the accuracy of the operation results by printing the value of the variable. .

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