Default string initialization NULL or Empty

Question

I have always initialized my strings to NULL  with the thinking that NULL means the absence of a value and  quot  quot  or String Empty is a valid value   I have seen more examples lately of code where String Empty is considered the default value or represents no value   This strikes me as odd  with the newly added nullable types in c  it seems like we are taking strides backwards with strings by not using the NULL to represent  No Value   What do you use as the default initializer and why  Edit  Based on the answers I futher my further thoughts  Avoiding error handling If the value shouldn t be null  why did it get set to NULL in the first place   Perhaps it would be better to identify the error at the place where it occurs rather than cover it up through out the rest of your codebase   Avoiding null checks If you are tired of doing null checks in code  wouldn t it be better to abstract the null checks   Perhaps wrap  or extend   the string methods to make them NULL safe  What happens if you constantly use String Empty and a null happens to work it s way into your system  do you start adding NULL checks anyways    I can t help but return to the opinion that it is laziness  Any DBA would slap you nine ways to silly if you used    instead of null in his her database  I think the same principles apply in programming and there should be somebody to smack those upside the head who use String Empty rather than NULL to represent no value   Related Questions  In C   should I use string Empty or String Empty or          What is the difference between String Empty and        Null or empty string to represent no data in table column

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Is it possible that this is an error avoidance technique  advisable or not     Since    is still a string  you would be able to call string functions on it that would result in an exception if it was NULL

User · Answer

I think there s no reason not to use null for an unassigned  or at this place in a program flow not occurring  value  If you want to distinguish  there s   null  If you just want to check for a certain value and don t care whether it s null or something different  String Equals  XXX  MyStringVar  does just fine

User · Answer

It depends on the situation  In most cases I use String Empty because I don t want to be doing null checks every time I attempt to use a string  It makes the code a lot simpler and you are less likely to introduce unwanted NullReferenceException crashes   I only set the string to null when I need to know if it has been set or not and where an empty string is something valid to set it to  In practice  I find these situations rare

User · Answer

This is actually a gaping hole in the C  language   There is no way to define a string that cannot be null   This causes problems as simple as the one you are describing  which forces programmers to make a decision they shouldn t have to make  since in many cases NULL and String Empty mean the same thing   That  in turn  can later force other programmers to have to handle both NULL and String Empty  which is annoying   A bigger problem is that databases allow you to define fields that map to a C  string  but database fields can be defined as NOT NULL   So  there is no way to accurately represent  say  a varchar  100   NOT NULL field in SQL Server using a C  type   Other languages  such as Spec    do allow this   In my opinion  C  s inability to define a string that doesn t allow null is just as bad as its previous inability to define an int that does allow null   To completely answer your question  I always use empty string for default initialization because it is more similar to how database data types work   Edit  This statement was very unclear   It should read  I use empty string for default initialization when NULL is a superfluous state  much in the same way I set up a database column as NOT NULL if NULL would be a superfluous state   Similarly  many of my DB columns are set up as NOT NULL  so when I bring those into a C  string  the string will be empty or have a value  but will never be NULL   In other words  I only initialize a string to NULL if null has a meaning that is distinct from the meaning of String Empty  and I find that case to be less than common  but people here have given legitimate examples of this case

User · Answer

For most software that isn t actually string-processing software  program logic ought not to depend on the content of string variables   Whenever I see something like this in a program   if  s     value     I get a bad feeling   Why is there a string literal in this method   What s setting s   Does it know that logic depends on the value of the string   Does it know that it has to be lower case to work   Should I be fixing this by changing it to use String Compare   Should I be creating an Enum and parsing into it   From this perspective  one gets to a philosophy of code that s pretty simple   you avoid examining a string s contents wherever possible   Comparing a string to String Empty is really just a special case of comparing it to a literal   it s something to avoid doing unless you really have to   Knowing this  I don t blink when I see something like this in our code base   string msg   Validate item   if  msg    null       DisplayErrorMessage msg      return      I know that Validate would never return String Empty  because we write better code than that   Of course  the rest of the world doesn t work like this   When your program is dealing with user input  databases  files  and so on  you have to account for other philosophies   There  it s the job of your code to impose order on chaos   Part of that order is knowing when an empty string should mean String Empty and when it should mean null    Just to make sure I wasn t talking out of my ass  I just searched our codebase for  String IsNullOrEmpty    All 54 occurrences of it are in methods that process user input  return values from Python scripts  examine values retrieved from external APIs  etc

User · Answer

An empty string is a value  a piece of text which  incidentally  happens not to contain any letters   Null signifies no-value   I initialize variables to null when I wish to indicate that they do not point to or contain actual values - when the intent is for no-value

User · Answer

seems like this is a special case of the http   en wikipedia org wiki Null Object pattern

User · Answer

I always initialise them as NULL   I always use string IsNullOrEmpty someString  to check it s value   Simple

User · Answer

According to MSDN      By initializing strings with the Empty value instead of null  you can reduce the chances of a NullReferenceException occurring     Always using IsNullOrEmpty   is good practice nevertheless

User · Answer

I either set it to    or null - I always check by using String IsNullOrEmpty  so either is fine   But the inner geek in me says I should set it to null before I have a proper value for it

User · Answer

Is it possible that this is an error avoidance technique  advisable or not     Since    is still a string  you would be able to call string functions on it that would result in an exception if it was NULL

User · Answer

1 for distinguishing between  empty  and NULL   I agree that  empty  should mean  valid  but blank  and  NULL  should mean  invalid    So I d answer your question like this   empty when I want a valid default value that may or may not be changed  for example  a user s middle name   NULL when it is an error if the ensuing code does not set the value explicitly

User · Answer

Strings aren t value types  and never will be  -

User · Answer

Strings aren t value types  and never will be  -

User · Answer

I always declare string with string empty

User · Answer

seems like this is a special case of the http   en wikipedia org wiki Null Object pattern

User · Answer

I either set it to    or null - I always check by using String IsNullOrEmpty  so either is fine   But the inner geek in me says I should set it to null before I have a proper value for it

User · Answer

I always initialise them as NULL   I always use string IsNullOrEmpty someString  to check it s value   Simple

User · Answer

According to MSDN      By initializing strings with the Empty value instead of null  you can reduce the chances of a NullReferenceException occurring     Always using IsNullOrEmpty   is good practice nevertheless

User · Answer

It depends   Do you need to be able to tell if the value is missing  is it possible for it to not be defined    Is the empty string a valid value for the usage of that string   If you answered  yes  to both  then you ll want to use null   Otherwise you can t tell the difference between  no value  and  empty string    If you don t need to know if there s no value then the empty string is probably safer  as it allows you to skip null checks wherever you use it

User · Answer

This is actually a gaping hole in the C  language   There is no way to define a string that cannot be null   This causes problems as simple as the one you are describing  which forces programmers to make a decision they shouldn t have to make  since in many cases NULL and String Empty mean the same thing   That  in turn  can later force other programmers to have to handle both NULL and String Empty  which is annoying   A bigger problem is that databases allow you to define fields that map to a C  string  but database fields can be defined as NOT NULL   So  there is no way to accurately represent  say  a varchar  100   NOT NULL field in SQL Server using a C  type   Other languages  such as Spec    do allow this   In my opinion  C  s inability to define a string that doesn t allow null is just as bad as its previous inability to define an int that does allow null   To completely answer your question  I always use empty string for default initialization because it is more similar to how database data types work   Edit  This statement was very unclear   It should read  I use empty string for default initialization when NULL is a superfluous state  much in the same way I set up a database column as NOT NULL if NULL would be a superfluous state   Similarly  many of my DB columns are set up as NOT NULL  so when I bring those into a C  string  the string will be empty or have a value  but will never be NULL   In other words  I only initialize a string to NULL if null has a meaning that is distinct from the meaning of String Empty  and I find that case to be less than common  but people here have given legitimate examples of this case

User · Answer

I always declare string with string empty

User · Answer

An empty string is a value  a piece of text which  incidentally  happens not to contain any letters   Null signifies no-value   I initialize variables to null when I wish to indicate that they do not point to or contain actual values - when the intent is for no-value

User · Answer

Why do you want your string to be initialized at all  You don t have to initialize a variable when you declare one  and IMO  you should only do so when the value you are assigning is valid in the context of the code block   I see this a lot   string name   null     or String Empty if  condition      name    foo     else     name    bar      return name    Not initializing to null would be just as effective  Furthermore  most often you want a value to be assigned  By initializing to null  you can potentially miss code paths that don t assign a value  Like so   string name   null     or String Empty if  condition      name    foo     else if  othercondition      name    bar      return name    returns null when condition and othercondition are false   When you don t initialize to null  the compiler will generate an error saying that not all code paths assign a value  Of course  this is a very simple example     Matthijs

User · Answer

Strings aren t value types  and never will be  -

User · Answer

Strings aren t value types  and never will be  -

User · Answer

1 for distinguishing between  empty  and NULL   I agree that  empty  should mean  valid  but blank  and  NULL  should mean  invalid    So I d answer your question like this   empty when I want a valid default value that may or may not be changed  for example  a user s middle name   NULL when it is an error if the ensuing code does not set the value explicitly

User · Answer

For most software that isn t actually string-processing software  program logic ought not to depend on the content of string variables   Whenever I see something like this in a program   if  s     value     I get a bad feeling   Why is there a string literal in this method   What s setting s   Does it know that logic depends on the value of the string   Does it know that it has to be lower case to work   Should I be fixing this by changing it to use String Compare   Should I be creating an Enum and parsing into it   From this perspective  one gets to a philosophy of code that s pretty simple   you avoid examining a string s contents wherever possible   Comparing a string to String Empty is really just a special case of comparing it to a literal   it s something to avoid doing unless you really have to   Knowing this  I don t blink when I see something like this in our code base   string msg   Validate item   if  msg    null       DisplayErrorMessage msg      return      I know that Validate would never return String Empty  because we write better code than that   Of course  the rest of the world doesn t work like this   When your program is dealing with user input  databases  files  and so on  you have to account for other philosophies   There  it s the job of your code to impose order on chaos   Part of that order is knowing when an empty string should mean String Empty and when it should mean null    Just to make sure I wasn t talking out of my ass  I just searched our codebase for  String IsNullOrEmpty    All 54 occurrences of it are in methods that process user input  return values from Python scripts  examine values retrieved from external APIs  etc

User · Answer

For most software that isn t actually string-processing software  program logic ought not to depend on the content of string variables   Whenever I see something like this in a program   if  s     value     I get a bad feeling   Why is there a string literal in this method   What s setting s   Does it know that logic depends on the value of the string   Does it know that it has to be lower case to work   Should I be fixing this by changing it to use String Compare   Should I be creating an Enum and parsing into it   From this perspective  one gets to a philosophy of code that s pretty simple   you avoid examining a string s contents wherever possible   Comparing a string to String Empty is really just a special case of comparing it to a literal   it s something to avoid doing unless you really have to   Knowing this  I don t blink when I see something like this in our code base   string msg   Validate item   if  msg    null       DisplayErrorMessage msg      return      I know that Validate would never return String Empty  because we write better code than that   Of course  the rest of the world doesn t work like this   When your program is dealing with user input  databases  files  and so on  you have to account for other philosophies   There  it s the job of your code to impose order on chaos   Part of that order is knowing when an empty string should mean String Empty and when it should mean null    Just to make sure I wasn t talking out of my ass  I just searched our codebase for  String IsNullOrEmpty    All 54 occurrences of it are in methods that process user input  return values from Python scripts  examine values retrieved from external APIs  etc

User · Answer

Null should only be used in cases where a value is optional  If the value is not optional  like  Name  or  Address    then the value should never be null  This applies to databases as well as POCOs and the user interface  Null means  this value is optional  and is currently absent    If your field is not optional  then you should initialize it as the empty string  To initialize it as null would place your object into an invalid state  invalid by your own data model    Personally I would rather strings to not be nullable by default  but instead only nullable if we declare a  string    Although perhaps this not feasible or logical at a deeper level  not sure

User · Answer

I think there s no reason not to use null for an unassigned  or at this place in a program flow not occurring  value  If you want to distinguish  there s   null  If you just want to check for a certain value and don t care whether it s null or something different  String Equals  XXX  MyStringVar  does just fine

User · Answer

1 for distinguishing between  empty  and NULL   I agree that  empty  should mean  valid  but blank  and  NULL  should mean  invalid    So I d answer your question like this   empty when I want a valid default value that may or may not be changed  for example  a user s middle name   NULL when it is an error if the ensuing code does not set the value explicitly

User · Answer

An empty string is a value  a piece of text which  incidentally  happens not to contain any letters   Null signifies no-value   I initialize variables to null when I wish to indicate that they do not point to or contain actual values - when the intent is for no-value

User · Answer

Reiterating Tomalak response  keep in mind that when you assign a string variable to an initial value of null  your variable is no longer a string object  same with any object in C   So  if you attempt to access any methods or properties for your variable and you are assuming it is a string object  you will get the NullReferenceException exception

User · Answer

It depends   Do you need to be able to tell if the value is missing  is it possible for it to not be defined    Is the empty string a valid value for the usage of that string   If you answered  yes  to both  then you ll want to use null   Otherwise you can t tell the difference between  no value  and  empty string    If you don t need to know if there s no value then the empty string is probably safer  as it allows you to skip null checks wherever you use it

User · Answer

I always declare string with string empty

User · Answer

Why do you want your string to be initialized at all  You don t have to initialize a variable when you declare one  and IMO  you should only do so when the value you are assigning is valid in the context of the code block   I see this a lot   string name   null     or String Empty if  condition      name    foo     else     name    bar      return name    Not initializing to null would be just as effective  Furthermore  most often you want a value to be assigned  By initializing to null  you can potentially miss code paths that don t assign a value  Like so   string name   null     or String Empty if  condition      name    foo     else if  othercondition      name    bar      return name    returns null when condition and othercondition are false   When you don t initialize to null  the compiler will generate an error saying that not all code paths assign a value  Of course  this is a very simple example     Matthijs

User · Answer

According to MSDN      By initializing strings with the Empty value instead of null  you can reduce the chances of a NullReferenceException occurring     Always using IsNullOrEmpty   is good practice nevertheless

User · Answer

I always declare string with string empty

User · Answer

I always initialise them as NULL   I always use string IsNullOrEmpty someString  to check it s value   Simple

User · Answer

I either set it to    or null - I always check by using String IsNullOrEmpty  so either is fine   But the inner geek in me says I should set it to null before I have a proper value for it

User · Answer

For most software that isn t actually string-processing software  program logic ought not to depend on the content of string variables   Whenever I see something like this in a program   if  s     value     I get a bad feeling   Why is there a string literal in this method   What s setting s   Does it know that logic depends on the value of the string   Does it know that it has to be lower case to work   Should I be fixing this by changing it to use String Compare   Should I be creating an Enum and parsing into it   From this perspective  one gets to a philosophy of code that s pretty simple   you avoid examining a string s contents wherever possible   Comparing a string to String Empty is really just a special case of comparing it to a literal   it s something to avoid doing unless you really have to   Knowing this  I don t blink when I see something like this in our code base   string msg   Validate item   if  msg    null       DisplayErrorMessage msg      return      I know that Validate would never return String Empty  because we write better code than that   Of course  the rest of the world doesn t work like this   When your program is dealing with user input  databases  files  and so on  you have to account for other philosophies   There  it s the job of your code to impose order on chaos   Part of that order is knowing when an empty string should mean String Empty and when it should mean null    Just to make sure I wasn t talking out of my ass  I just searched our codebase for  String IsNullOrEmpty    All 54 occurrences of it are in methods that process user input  return values from Python scripts  examine values retrieved from external APIs  etc

User · Answer

This is actually a gaping hole in the C  language   There is no way to define a string that cannot be null   This causes problems as simple as the one you are describing  which forces programmers to make a decision they shouldn t have to make  since in many cases NULL and String Empty mean the same thing   That  in turn  can later force other programmers to have to handle both NULL and String Empty  which is annoying   A bigger problem is that databases allow you to define fields that map to a C  string  but database fields can be defined as NOT NULL   So  there is no way to accurately represent  say  a varchar  100   NOT NULL field in SQL Server using a C  type   Other languages  such as Spec    do allow this   In my opinion  C  s inability to define a string that doesn t allow null is just as bad as its previous inability to define an int that does allow null   To completely answer your question  I always use empty string for default initialization because it is more similar to how database data types work   Edit  This statement was very unclear   It should read  I use empty string for default initialization when NULL is a superfluous state  much in the same way I set up a database column as NOT NULL if NULL would be a superfluous state   Similarly  many of my DB columns are set up as NOT NULL  so when I bring those into a C  string  the string will be empty or have a value  but will never be NULL   In other words  I only initialize a string to NULL if null has a meaning that is distinct from the meaning of String Empty  and I find that case to be less than common  but people here have given legitimate examples of this case

User · Answer

An empty string is a value  a piece of text which  incidentally  happens not to contain any letters   Null signifies no-value   I initialize variables to null when I wish to indicate that they do not point to or contain actual values - when the intent is for no-value

User · Answer

seems like this is a special case of the http   en wikipedia org wiki Null Object pattern

User · Answer

This is actually a gaping hole in the C  language   There is no way to define a string that cannot be null   This causes problems as simple as the one you are describing  which forces programmers to make a decision they shouldn t have to make  since in many cases NULL and String Empty mean the same thing   That  in turn  can later force other programmers to have to handle both NULL and String Empty  which is annoying   A bigger problem is that databases allow you to define fields that map to a C  string  but database fields can be defined as NOT NULL   So  there is no way to accurately represent  say  a varchar  100   NOT NULL field in SQL Server using a C  type   Other languages  such as Spec    do allow this   In my opinion  C  s inability to define a string that doesn t allow null is just as bad as its previous inability to define an int that does allow null   To completely answer your question  I always use empty string for default initialization because it is more similar to how database data types work   Edit  This statement was very unclear   It should read  I use empty string for default initialization when NULL is a superfluous state  much in the same way I set up a database column as NOT NULL if NULL would be a superfluous state   Similarly  many of my DB columns are set up as NOT NULL  so when I bring those into a C  string  the string will be empty or have a value  but will never be NULL   In other words  I only initialize a string to NULL if null has a meaning that is distinct from the meaning of String Empty  and I find that case to be less than common  but people here have given legitimate examples of this case

User · Answer

It depends on the situation  In most cases I use String Empty because I don t want to be doing null checks every time I attempt to use a string  It makes the code a lot simpler and you are less likely to introduce unwanted NullReferenceException crashes   I only set the string to null when I need to know if it has been set or not and where an empty string is something valid to set it to  In practice  I find these situations rare

User · Answer

Is it possible that this is an error avoidance technique  advisable or not     Since    is still a string  you would be able to call string functions on it that would result in an exception if it was NULL

User · Answer

1 for distinguishing between  empty  and NULL   I agree that  empty  should mean  valid  but blank  and  NULL  should mean  invalid    So I d answer your question like this   empty when I want a valid default value that may or may not be changed  for example  a user s middle name   NULL when it is an error if the ensuing code does not set the value explicitly

User · Answer

Reiterating Tomalak response  keep in mind that when you assign a string variable to an initial value of null  your variable is no longer a string object  same with any object in C   So  if you attempt to access any methods or properties for your variable and you are assuming it is a string object  you will get the NullReferenceException exception

User · Answer

According to MSDN      By initializing strings with the Empty value instead of null  you can reduce the chances of a NullReferenceException occurring     Always using IsNullOrEmpty   is good practice nevertheless

User · Answer

It depends on the situation  In most cases I use String Empty because I don t want to be doing null checks every time I attempt to use a string  It makes the code a lot simpler and you are less likely to introduce unwanted NullReferenceException crashes   I only set the string to null when I need to know if it has been set or not and where an empty string is something valid to set it to  In practice  I find these situations rare

User · Answer

seems like this is a special case of the http   en wikipedia org wiki Null Object pattern

User · Answer

It depends on the situation  In most cases I use String Empty because I don t want to be doing null checks every time I attempt to use a string  It makes the code a lot simpler and you are less likely to introduce unwanted NullReferenceException crashes   I only set the string to null when I need to know if it has been set or not and where an empty string is something valid to set it to  In practice  I find these situations rare

User · Answer

It depends   Do you need to be able to tell if the value is missing  is it possible for it to not be defined    Is the empty string a valid value for the usage of that string   If you answered  yes  to both  then you ll want to use null   Otherwise you can t tell the difference between  no value  and  empty string    If you don t need to know if there s no value then the empty string is probably safer  as it allows you to skip null checks wherever you use it

User · Answer

I either set it to    or null - I always check by using String IsNullOrEmpty  so either is fine   But the inner geek in me says I should set it to null before I have a proper value for it

User · Answer

Is it possible that this is an error avoidance technique  advisable or not     Since    is still a string  you would be able to call string functions on it that would result in an exception if it was NULL

User · Answer

It depends   Do you need to be able to tell if the value is missing  is it possible for it to not be defined    Is the empty string a valid value for the usage of that string   If you answered  yes  to both  then you ll want to use null   Otherwise you can t tell the difference between  no value  and  empty string    If you don t need to know if there s no value then the empty string is probably safer  as it allows you to skip null checks wherever you use it

User · Answer

Null should only be used in cases where a value is optional  If the value is not optional  like  Name  or  Address    then the value should never be null  This applies to databases as well as POCOs and the user interface  Null means  this value is optional  and is currently absent    If your field is not optional  then you should initialize it as the empty string  To initialize it as null would place your object into an invalid state  invalid by your own data model    Personally I would rather strings to not be nullable by default  but instead only nullable if we declare a  string    Although perhaps this not feasible or logical at a deeper level  not sure

User · Answer

I always initialise them as NULL   I always use string IsNullOrEmpty someString  to check it s value   Simple

[c#] Default string initialization: NULL or Empty?

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