Wednesday, April 9, 2014
Here's an important interview question asked mostly in interviews of top companies like TCS, Infosys, Capgemini, Cognizant, JP Morgan, Nomura, etc
| var | dynamic |
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Introduced in C# 3.0 |
Introduced in C# 4.0 |
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Statically typed – This means the type of variable declared is decided by the compiler at compile time. |
Dynamically typed - This means the type of variable declared is decided by the compiler at runtime time. |
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Need to initialize at the time of declaration. e.g., var str=”I am a string”;Looking at the value assigned to the variable str, the compiler will treat the variable str as string. |
No need to initialize at the time of declaration. e.g., dynamic str; str=”I am a string”; //Works fine and compilesstr=2; //Works fine and compiles |
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Errors are caught at compile time. Since the compiler knows about the type and the methods and properties of the type at the compile time itself |
Errors are caught at runtime Since the compiler comes to about the type and the methods and properties of the type at the run time. |
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Visual Studio shows intellisense since the type of variable assigned is known to compiler. |
Intellisense is not available since the type and its related methods and properties can be known at run time only |
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e.g., var obj1; will throw a compile error since the variable is not initialized. The compiler needs that this variable should be initialized so that it can infer a type from the value. |
e.g., dynamic obj1; will compile; |
e.g. var obj1=1; will compile var obj1=” I am a string”; |
e.g. dynamic obj1=1; will compile and run dynamic obj1=” I am a string”; will compile and run since the compiler creates the type for obj1 as System.Int32 and then recreates the type as string when the value “I am a string” was assigned to it. This code will work fine. |
by The Opening Batsman · 0
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