C++ function return value revealed: type interpretation and meaning analysis

C The type of function return value specifies the data type returned and conveys the meaning of the function function. For example, a null value indicates that the function does not return any value. The success or failure status is expressed by an integer or Boolean. The specified result indicates the function operation. actual return value. Common return value types include built-in types (integers, decimals, etc.), pointer types (pointing to memory locations), reference types (aliases of variables or objects), and class types (user-defined data types). Through practical cases (summation function, email address verification function), we understood the application of different return value types in different functions.

C function return value revealed: type interpretation and meaning analysis

Introduction

In C programming, the return value of a function is crucial. It provides a way to obtain results or information from the function. This article will delve into the return value type of C functions, analyze its meaning, and deepen understanding through practical cases.

Return value type

The return value type of a function specifies the data type of the value returned by the function. It can be a built-in type (such as int, float) or a custom type. The following are some common return value types:

• Built-in types: is used to represent basic values, such as integers, decimals, and characters.
• Pointer type: Points to a specific memory location. Usually used to return an object or array.
• Reference type: Provides an alias for a variable or object. Can be used to return a reference to an object.
• Class type: User-defined data type. Returns a newly created or existing class instance.

Return value meaning

The return value type of a function not only specifies the data type returned, but also conveys important information about the function's functionality. Common meanings are as follows:

• Null value: void type indicates that the function does not return any value.
• Success or failure: Integer or Boolean type (bool) indicates whether the function execution is successful. For example, 0 indicates success and -1 indicates failure.
• Specify the result: The actual value returned represents the result of the function operation. For example, the int returned in the sum function is the sum of two numbers.

Practical case

Function to find the sum of two numbers:

int sum(int a, int b) {
  return a + b;
}

This function returns two The sum of integers, of type int, indicates that the function executes successfully and returns an int result.

Function to verify email address:

bool is_valid_email(string email) {
  regex pattern(R"([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,})");
  return regex_match(email, pattern);
}

This function returns a bool value indicating whether the email address is valid. true means valid, false means invalid.

Conclusion

The return value type of a C function not only defines the data type returned, but also conveys important meaning about the function's functionality. Understanding these types and using them correctly is key to writing efficient, meaningful C code.

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