C++ error: The function return type does not match the actual return value type. How should I modify it?

C is a very powerful programming language, but some errors will inevitably occur when writing programs. One of the common problems is the mismatch between the function return type and the actual return value type. This error is relatively common, but it can be very frustrating if you don't know how to solve it. Let's take a look at the reasons why this error occurs and how to correct it with specific examples.

Cause of the problem

In C, the return type of a function is determined when the function is defined. In other words, you need to explicitly specify the return type when defining a function. This return type must be the same type as the value ultimately returned by the function, otherwise type mismatch problems will occur.

The following is an example:

// 函数定义
int add(int a, int b)
{
    return a + b;
}

// 调用函数
int result = add(1, 2);

In the above code, we define an add function whose return type is int type. When calling the function, we assign the return value to a variable result of type int. In this case, the return type of the function is consistent with the type of the final return value, so there is no problem.

However, if the return type we specify in the function definition is inconsistent with the type of the final return value, a type mismatch problem will occur. The specific code is as follows:

// 函数定义
int add(int a, int b)
{
    return a + b + 0.5;
}

// 调用函数
int result = add(1, 2);

In the above code, What we return in the add function is a b 0.5, which is a double type value. But in the function definition, our return type is int type. This will cause type mismatch problems, and the compiler will prompt an error.

Solution

If there is a problem that the function return type does not match the actual return value type, the solution is also very simple. Just change the return type in the function definition to the type of the actual returned value. The following is the modified code:

// 函数定义
double add(int a, int b)
{
    return a + b + 0.5;
}

// 调用函数
double result = add(1, 2);

In the above code, we changed the return type of the add function from int to double, so that the double value of a b 0.5 can be correctly returned. When calling the function, we also assign the return value to a double type variable result, so that there will be no type mismatch problem.

In actual programming, it is common that the function return type does not match the actual return value type. When encountering this situation, we only need to pay attention to changing the return type in the function definition to the type of the actual return value. This can avoid type mismatch problems and make the program more stable and reliable.

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