PHP constants are constant character or numerical types defined in DEFINE. Commonly used fixed values such as 3.14 are considered this type of value. This is given in the predefined COMMON. Convenient to use throughout the entire process. This is all for frequent use during the development process.
When writing constants, be sure to pay attention to capitalization. I didn't pay attention to this problem at the beginning when I was writing, and ended up getting very frustrated while debugging.
Constant can be understood as a quantity whose value does not change; or after the constant value is defined, it can be used globally, but the constant is not fixed.
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PHP constants are constant character or numerical types defined in DEFINE. Commonly used fixed values such as 3.14 are considered this type of value. This is given in the predefined COMMON. Convenient to use throughout the entire process. This is all for frequent use during the development process.
What are constants? -PHP Chinese website Q&A-What are constants? -PHP Chinese website Q&A
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When writing constants, be sure to pay attention to capitalization. I didn't pay attention to this problem at the beginning when I was writing, and ended up getting very frustrated while debugging.
Constant can be understood as a quantity whose value does not change; or after the constant value is defined, it can be used globally, but the constant is not fixed.
常量可以理解为值不变的量（如圆周率）；或者是常量值被定义后，在脚本的其他任何地方都不可以被改变。