[Solved] Error ‘false‘ undeclared (first use in this function)

Error: ‘false’ undeclared (first use in this function)

When you knock the code with DEVC + +, you will report an error to the following program

bool ok(int t){
	//Determine whether the tth person's job is assigned or not; if it is not assigned then a[j] = 0, otherwise a[j] = 1. 
	int i;
	for(i=0;i<t;i++)
		if(a[i]==a[t])
			return false;
		return true;
}

analysis:

There are no these keywords in real C. There is no keyword bool in C and early C + +. Bool can be used, but bool is not a built-in type. It is defined through typedef or macros. It is usually defined as int type. Later, the built-in type bool appeared in C + +, and the values can only be true (1) and false (0).

Solution 1:

Change the file type to CPP

Solution 2:

Macro definition of bool:

typedef enum __bool { false = 0, true = 1, } bool;

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