How to convert C nullable int to int

Question

How do I convert a nullable int to an int  Suppose I have 2 type of int as below   int  v1    int v2     I want to assign v1 s value to v2  v2   v1  will cause an error  How do I convert v1 to v2

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If you know that v1 has a value  you can use the Value property   v2   v1 Value    Using the GetValueOrDefault method will assign the value if there is one  otherwise the default for the type  or a default value that you specify   v2   v1 GetValueOrDefault       assigns zero if v1 has no value  v2   v1 GetValueOrDefault -1      assigns -1 if v1 has no value   You can use the HasValue property to check if v1 has a value   if  v1 HasValue      v2   v1 Value      There is also language support for the GetValueOrDefault T  method   v2   v1    -1

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Int nullable to int conversion can be done like so   v2  int v1

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If the default value for a given type is an acceptable result   if  v1 HasValue      v2   v1 GetValueOrDefault     If you want a different default value when the result is undefined   v2   v1 GetValueOrDefault 255         or any valid value for int in place of 255  If you just want the value returned  no matter if the method failed or not    v2   v1 GetValueOrDefault       NET 4 7 2   GetValueOrDefault   returns the field value without any checking

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Like this   if v1 HasValue     v2 v1 Value

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You can use the Value property for assignment   v2   v1 Value

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All you need is     v2  v1 GetValueOrDefault

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You can t do it if v1 is null  but you can check with an operator   v2   v1    0

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It will assign value of v1 to v2 if it is not null  else it will take a default value as zero   v2 v1  0   Or below is the other way to write it   v2   v1 HasValue v1 0

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As far as I m concerned the best solution is using GetValueOrDefault   method    v2   v1 GetValueOrDefault

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You could do  v2   v1 HasValue   v1 Value   v2

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it s possible with v2   Convert ToInt32 v1

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int v2  Int32 Parse v1 ToString

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GetValueOrDefault     retrieves the value of the object  If it is null  it returns the default value of int   which is 0   Example      v2  v1 GetValueOrDefault

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In C  7 1 and later  type can be inferred by using the default literal instead of the default operator so it can be written as below   v2   v1    default

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I am working on C  9 and  NET 5  example foo is nullable int  I need get int value of foo var foo    context as AccountTransfer  TransferSide  int value2   0  if  foo    null        value2   foo Value     See more at https   docs microsoft com en-us dotnet csharp language-reference builtin-types nullable-value-types examination-of-an-instance-of-a-nullable-value-type

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The other answers so far are all correct  I just wanted to add one more that s slightly cleaner   v2   v1    default int     Any Nullable lt T gt  is implicitly convertible to its T  PROVIDED that the entire expression being evaluated can never result in a null assignment to a ValueType  So  the null-coalescing operator    is just syntax sugar for the ternary operator   v2   v1    null   default int    v1       which is in turn syntax sugar for an if else   if v1  null     v2   default int   else    v2   v1      Also  as of  NET 4 0  Nullable lt T gt  has a  GetValueOrDefault    method  which is a null-safe getter that basically performs the null-coalescing shown above  so this works too   v2   v1 GetValueOrDefault

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A simple conversion between v1 and v2 is not possible because v1 has a larger domain of values than v2   It s everything v1 can hold plus the null state   To convert you need to explicitly state what value in int will be used to map the null state   The simplest way to do this is the    operator  v2   v1    0      maps null of v1 to 0   This can also be done in long form   int v2  if  v1 HasValue      v2   v1 Value    else     v2   0

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Depending on your usage context  you may use C  7 s pattern-matching feature   int  v1   100  if  v1 is int v2        Console WriteLine   I m not nullable anymore   v2         EDIT   Since some people are downvoting without leaving an explanation  I d like to add some details to explain the rationale for including this as a viable solution    C  7 s pattern matching now allows us check the type of a value and cast it implicitly  In the above snippet  the if-condition will only pass when the value stored in v1 is type-compatible to the type for v2  which in this case is int  It follows that when the value for v1 is null  the if-condition will fail since null cannot be assigned to an int  More properly  null is not an int  I d like to highlight that the that this solution may not always be the optimal choice  As I suggest  I believe this will depend on the developer s exact usage context  If you already have an int  and want to conditionally operate on its value if-and-only-if the assigned value is not null  this is the only time it is safe to convert a nullable int to a regular int without losing information   then pattern matching is perhaps one of the most concise ways to do this

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