How do you convert a C string to an int

Question

Possible Duplicate    How to parse a string to an int in C          How do you convert a C   string to an int   Assume you are expecting the string to have actual numbers in it   1    345    38944   for example    Also  let s assume you don t have boost  and you really want to do it the C   way  not the crufty old C way

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Perhaps I am misunderstanding the question  by why exactly would you not want to use atoi  I see no point in reinventing the wheel   Am I just missing the point here

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Perhaps I am misunderstanding the question  by why exactly would you not want to use atoi  I see no point in reinventing the wheel   Am I just missing the point here

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Let me add my vote for boost  lexical cast   include  lt boost lexical cast hpp gt   int val   boost  lexical cast lt int gt  strval      It throws bad lexical cast on error

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Use the C   streams   std  string       plop  123    std  stringstream str plop   int x   str  gt  gt  x      Lets not forget to error checking    if   str            The conversion failed          Need to do something here          Maybe throw an exception     PS  This basic principle is how the boost library lexical cast lt  gt  works   My favorite method is the boost lexical cast lt  gt    include  lt boost lexical cast hpp gt   int x   boost  lexical cast lt int gt   123      It provides a method to convert between a string and number formats and back again  Underneath it uses a string stream so anything that can be marshaled into a stream and then un-marshaled from a stream  Take a look at the    and  lt  lt  operators

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Use atoi

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Perhaps I am misunderstanding the question  by why exactly would you not want to use atoi  I see no point in reinventing the wheel   Am I just missing the point here

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I have used something like the following in C   code before    include  lt sstream gt  int main         char  str    1234       std  stringstream s str  str        int i      s str  gt  gt  i

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C   FAQ Lite   39 2  How do I convert a std  string to a number   https   isocpp org wiki faq misc-technical-issues convert-string-to-num

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include  lt sstream gt      st is input string int result  stringstream st   gt  gt  result

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Use atoi

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in  stdapi h   StrToInt   This function tells you the result  and how many characters participated in the conversion

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I have used something like the following in C   code before    include  lt sstream gt  int main         char  str    1234       std  stringstream s str  str        int i      s str  gt  gt  i

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include  lt sstream gt      st is input string int result  stringstream st   gt  gt  result

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Use the C   streams   std  string       plop  123    std  stringstream str plop   int x   str  gt  gt  x      Lets not forget to error checking    if   str            The conversion failed          Need to do something here          Maybe throw an exception     PS  This basic principle is how the boost library lexical cast lt  gt  works   My favorite method is the boost lexical cast lt  gt    include  lt boost lexical cast hpp gt   int x   boost  lexical cast lt int gt   123      It provides a method to convert between a string and number formats and back again  Underneath it uses a string stream so anything that can be marshaled into a stream and then un-marshaled from a stream  Take a look at the    and  lt  lt  operators

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include  lt sstream gt      st is input string int result  stringstream st   gt  gt  result

User · Answer

Let me add my vote for boost  lexical cast   include  lt boost lexical cast hpp gt   int val   boost  lexical cast lt int gt  strval      It throws bad lexical cast on error

User · Answer

Use the C   streams   std  string       plop  123    std  stringstream str plop   int x   str  gt  gt  x      Lets not forget to error checking    if   str            The conversion failed          Need to do something here          Maybe throw an exception     PS  This basic principle is how the boost library lexical cast lt  gt  works   My favorite method is the boost lexical cast lt  gt    include  lt boost lexical cast hpp gt   int x   boost  lexical cast lt int gt   123      It provides a method to convert between a string and number formats and back again  Underneath it uses a string stream so anything that can be marshaled into a stream and then un-marshaled from a stream  Take a look at the    and  lt  lt  operators

User · Answer

include  lt sstream gt      st is input string int result  stringstream st   gt  gt  result

User · Answer

Use atoi

User · Answer

Use the C   streams   std  string       plop  123    std  stringstream str plop   int x   str  gt  gt  x      Lets not forget to error checking    if   str            The conversion failed          Need to do something here          Maybe throw an exception     PS  This basic principle is how the boost library lexical cast lt  gt  works   My favorite method is the boost lexical cast lt  gt    include  lt boost lexical cast hpp gt   int x   boost  lexical cast lt int gt   123      It provides a method to convert between a string and number formats and back again  Underneath it uses a string stream so anything that can be marshaled into a stream and then un-marshaled from a stream  Take a look at the    and  lt  lt  operators

User · Answer

in  stdapi h   StrToInt   This function tells you the result  and how many characters participated in the conversion

User · Answer

in  stdapi h   StrToInt   This function tells you the result  and how many characters participated in the conversion

User · Answer

Let me add my vote for boost  lexical cast   include  lt boost lexical cast hpp gt   int val   boost  lexical cast lt int gt  strval      It throws bad lexical cast on error

User · Answer

C   FAQ Lite   39 2  How do I convert a std  string to a number   https   isocpp org wiki faq misc-technical-issues convert-string-to-num

User · Answer

C   FAQ Lite   39 2  How do I convert a std  string to a number   https   isocpp org wiki faq misc-technical-issues convert-string-to-num

User · Answer

in  stdapi h   StrToInt   This function tells you the result  and how many characters participated in the conversion

User · Answer

C   FAQ Lite   39 2  How do I convert a std  string to a number   https   isocpp org wiki faq misc-technical-issues convert-string-to-num

User · Answer

Perhaps I am misunderstanding the question  by why exactly would you not want to use atoi  I see no point in reinventing the wheel   Am I just missing the point here

User · Answer

I have used something like the following in C   code before    include  lt sstream gt  int main         char  str    1234       std  stringstream s str  str        int i      s str  gt  gt  i

User · Answer

I have used something like the following in C   code before    include  lt sstream gt  int main         char  str    1234       std  stringstream s str  str        int i      s str  gt  gt  i

User · Answer

Use atoi

User · Answer

Let me add my vote for boost  lexical cast   include  lt boost lexical cast hpp gt   int val   boost  lexical cast lt int gt  strval      It throws bad lexical cast on error

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