Return Statement (C); 2 minutes to read +2; In this article. Terminates the execution of a function and returns control to the calling function (or to the operating system if you transfer control from the main function). Execution resumes in the calling function at the point immediately following the call. If a function is declared to return a value, and fails to do so, the result is undefined behavior (in C). One possible result is seeming to work, which is pretty much what you're seeing here. As an aside, in C, you wouldn't actually have undefined behavior - in C, you get undefined behavior only if you try to use the return value, and the. Sep 18, 2013 General C Programming; Dev C Process exited with return value. Dev C Process exited with return value: apurvaKumar. My code is compiling successfully but immediately after that I'm getting the message 'Process exited with return value '. The code is working fine in ideone.com. C for loop - A for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times. Dec 17, 2018 (This is essentially the definition of a C03 POD type. Because the definition has changed in the C11 standard, we don't recommend using std::ispod for this test.) Otherwise, the caller assumes the responsibility of allocating memory and passing a pointer for the return value as the first argument.
In modern C++, in most scenarios, the preferred way to report and handle both logic errors and runtime errors is to use exceptions. This is especially true when the stack might contain several function calls between the function that detects the error and the function that has the context to know how to handle it. Exceptions provide a formal, well-defined way for code that detects errors to pass the information up the call stack.
Program errors are generally divided into two categories: logic errors that are caused by programming mistakes, for example, an 'index out of range' error, and runtime errors that are beyond the control of programmer, for example, a 'network service unavailable' error. In C-style programming and in COM, error reporting is managed either by returning a value that represents an error code or a status code for a particular function, or by setting a global variable that the caller may optionally retrieve after every function call to see whether errors were reported. For example, COM programming uses the HRESULT return value to communicate errors to the caller, and the Win32 API has the GetLastError function to retrieve the last error that was reported by the call stack. In both of these cases, it's up to the caller to recognize the code and respond to it appropriately. If the caller doesn't explicitly handle the error code, the program might crash without warning, or continue to execute with bad data and produce incorrect results.
Exceptions are preferred in modern C++ for the following reasons:
An exception forces calling code to recognize an error condition and handle it. Unhandled exceptions stop program execution.
An exception jumps to the point in the call stack that can handle the error. Lurssen mastering console vst download. Intermediate functions can let the exception propagate. They do not have to coordinate with other layers.
The exception stack-unwinding mechanism destroys all objects in scope according to well-defined rules after an exception is thrown.
An exception enables a clean separation between the code that detects the error and the code that handles the error.
The following simplified example shows the necessary syntax for throwing and catching exceptions in C++.
Exceptions in C++ resemble those in languages such as C# and Java. In the try block, if an exception is thrown it will be caught by the first associated catch block whose type matches that of the exception. In other words, execution jumps from the throw statement to the catch statement. If no usable catch block is found, std::terminate is invoked and the program exits. In C++, any type may be thrown; however, we recommend that you throw a type that derives directly or indirectly from std::exception. In the previous example, the exception type, invalid_argument, is defined in the standard library in the <stdexcept> header file. C++ does not provide, and does not require, a finally block to make sure that all resources are released if an exception is thrown. The resource acquisition is initialization (RAII) idiom, which uses smart pointers, provides the required functionality for resource cleanup. For more information, see How to: Design for Exception Safety. For information about the C++ stack-unwinding mechanism, see Exceptions and Stack Unwinding.
Basic guidelines
Robust error handling is challenging in any programming language. Although exceptions provide several features that support good error handling, they can't do all the work for you. To realize the benefits of the exception mechanism, keep exceptions in mind as you design your code.
Use asserts to check for errors that should never occur. Use exceptions to check for errors that might occur, for example, errors in input validation on parameters of public functions. For more information, see the section titled Exceptions vs. Assertions.
Use exceptions when the code that handles the error might be separated from the code that detects the error by one or more intervening function calls. Consider whether to use error codes instead in performance-critical loops when code that handles the error is tightly-coupled to the code that detects it.
For every function that might throw or propagate an exception, provide one of the three exception guarantees: the strong guarantee, the basic guarantee, or the nothrow (noexcept) guarantee. For more information, see How to: Design for Exception Safety.
Throw exceptions by value, catch them by reference. Don’t catch what you can't handle.
Don't use exception specifications, which are deprecated in C++11. For more information, see the section titled Exception specifications and noexcept.
Use standard library exception types when they apply. Derive custom exception types from the exception Class hierarchy.
Don't allow exceptions to escape from destructors or memory-deallocation functions.
Exceptions and performance
The exception mechanism has a very minimal performance cost if no exception is thrown. If an exception is thrown, the cost of the stack traversal and unwinding is roughly comparable to the cost of a function call. Additional data structures are required to track the call stack after a try block is entered, and additional instructions are required to unwind the stack if an exception is thrown. However, in most scenarios, the cost in performance and memory footprint is not significant. The adverse effect of exceptions on performance is likely to be significant only on very memory-constrained systems, or in performance-critical loops where an error is likely to occur regularly and the code to handle it is tightly coupled to the code that reports it. In any case, it's impossible to know the actual cost of exceptions without profiling and measuring. Even in those rare cases when the cost is significant, you can weigh it against the increased correctness, easier maintainability, and other advantages that are provided by a well-designed exception policy.
Exceptions vs. assertions
Exceptions and asserts are two distinct mechanisms for detecting run-time errors in a program. Use asserts to test for conditions during development that should never be true if all your code is correct. There is no point in handling such an error by using an exception because the error indicates that something in the code has to be fixed, and doesn't represent a condition that the program has to recover from at run time. An assert stops execution at the statement so that you can inspect the program state in the debugger; an exception continues execution from the first appropriate catch handler. Use exceptions to check error conditions that might occur at run time even if your code is correct, for example, 'file not found' or 'out of memory.' You might want to recover from these conditions, even if the recovery just outputs a message to a log and ends the program. Always check arguments to public functions by using exceptions. Even if your function is error-free, you might not have complete control over arguments that a user might pass to it.
C++ exceptions versus Windows SEH exceptions
Both C and C++ programs can use the structured exception handling (SEH) mechanism in the Windows operating system. The concepts in SEH resemble those in C++ exceptions, except that SEH uses the __try, __except, and __finally constructs instead of try and catch. In the Microsoft C++ compiler (MSVC), C++ exceptions are implemented for SEH. However, when you write C++ code, use the C++ exception syntax.
For more information about SEH, see Structured Exception Handling (C/C++).
Exception specifications and noexcept
Exception specifications were introduced in C++ as a way to specify the exceptions that a function might throw. However, exception specifications proved problematic in practice, and are deprecated in the C++11 draft standard. We recommend that you do not use exception specifications except for throw(), which indicates that the function allows no exceptions to escape. If you must use exception specifications of the type throw(type), be aware that MSVC departs from the standard in certain ways. For more information, see Exception Specifications (throw). The noexcept specifier is introduced in C++11 as the preferred alternative to throw().
See also
How to: Interface Between Exceptional and Non-Exceptional Code
C++ Language Reference
C++ Standard Library
Terminates the execution of a function and returns control to the calling function (or to the operating system if you transfer control from the main function). Execution resumes in the calling function at the point immediately following the call.
Syntax
Remarks
The expression clause, if present, is converted to the type specified in the function declaration, as if an initialization were being performed. Conversion from the type of the expression to the return type of the function can create temporary objects. For more information about how and when temporaries are created, see Temporary Objects.
C++ Return Value From Function
The value of the expression clause is returned to the calling function. If the expression is omitted, the return value of the function is undefined. Constructors and destructors, and functions of type void,cannot specify an expression in the return statement. Functions of all other types must specify an expression in the return statement.
When the flow of control exits the block enclosing the function definition, the result is the same as it would be if a return statement without an expression had been executed. This is invalid for functions that are declared as returning a value.
A function can have any number of return statements.
The following example uses an expression with a return statement to obtain the largest of two integers.
Example
C++ Return Two Values
See also
C++ Return By Value
Jump Statements
Keywords