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title: "main: Program Startup | Microsoft Docs"
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---
# main: Program Startup
A special function named `main` is the starting point of execution for all C and C++ programs. If you are writing code that adheres to the [!INCLUDE[TLA#tla_unicode](../atl-mfc-shared/reference/includes/tlasharptla_unicode_md.md)] programming model, you can use `wmain`, which is the wide-character version of `main`.  
  
 The `main` function is not predefined by the compiler. It must be supplied in the program text.  
  
 The declaration syntax for `main` is  
  
```  
int main();  
```  
  
 or, optionally,  
  
```  
int main(int argc, char *argv[], char *envp[]);  
```  
  
## Microsoft Specific  
 The declaration syntax for `wmain` is as follows:  
  
```  
int wmain( );  
```  
  
 or, optionally,  
  
```  
int wmain(int argc, wchar_t *argv[], wchar_t *envp[]);  
```  
  
 You can also use `_tmain`, which is defined in TCHAR.h. `_tmain` resolves to `main` unless _UNICODE is defined. In that case, `_tmain` resolves to `wmain`.  
  
 Alternatively, the `main` and `wmain` functions can be declared as returning `void` (no return value). If you declare `main` or `wmain` as returning `void`, you cannot return an exit code to the parent process or operating system by using a [return](../cpp/return-statement-in-program-termination-cpp.md) statement. To return an exit code when `main` or `wmain` is declared as `void`, you must use the [exit](../cpp/exit-function.md) function.  
  
**END Microsoft Specific**  
 The types for `argc` and `argv` are defined by the language. The names `argc`, `argv`, and `envp` are traditional, but are not required by the compiler. For more information and an example, see [Argument Definitions](../cpp/argument-definitions.md).  
  
## See Also  
 [Keywords](../cpp/keywords-cpp.md)   
 [Using wmain Instead of main](../cpp/using-wmain-instead-of-main.md)   
 [main Function Restrictions](../cpp/main-function-restrictions.md)