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# clock Function (C)
**ANSI 4.12.2.1** The era for the `clock` function  
  
 The `clock` function's era begins (with a value of 0) when the C program starts to execute. It returns times measured in 1/**CLOCKS_PER_SEC** (which equals 1/1000 for Microsoft C).  
  
## See Also  
 [Library Functions](../c-language/library-functions.md)