What does |= mean in c++

The |= operator in C is a bitwise OR operator, which performs a bitwise logical OR operation on two integers. If both bits are 1, the result is 1; otherwise, the result is 0 . It can be used to set or update bit flags, combination flags and check flags.

|= Operator in C

What is |= Operator?

|= is the bitwise OR operator in C, which performs a bitwise logical OR operation on two integers.

Operation Principle

Assume there are two integers a and b, and the |= operator performs a logical OR operation on each binary bit of a and b. If both bits are 1, the result is 1; otherwise, the result is 0.

For example:

a = 01101 (二进制) = 13 (十进制)
b = 10010 (二进制) = 18 (十进制)
a |= b = 11111 (二进制) = 31 (十进制)

Usage

|= operator can be used in various scenarios, including:

• Setting or updating bit flags: You can set or update single or multiple bits by performing the |= operation on a number with a bitmask.
• Combined flags: Multiple bit flags can be combined by performing the |= operation on them.
• Check Flags: You can check whether a number has a specific bit set by performing the |= operation on a number with a bitmask.

Example

// 设置第 3 位
int x = 0;
x |= (1 << 2); // x 现在为 00000100 (二进制)

// 组合标志
int flags = 0;
flags |= FLAG_READ; // 设置 FLAG_READ 标志
flags |= FLAG_WRITE; // 设置 FLAG_WRITE 标志

// 检查标志
if (flags & FLAG_READ) {
    // FLAG_READ 标志已设置
}

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