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Why do C and C++ allow the expression (int) + 4?



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17















(int) + 4*5;


Why is this possible? (tried with g++ and gcc.)










share|improve this question









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  • Even this is valid it is not a good idea to do that in a program because yes this is quite disturbing ^^

    – bruno
    6 hours ago








  • 1





    same as (int)-4*5

    – P__J__
    5 hours ago











  • Though "(int) (+4.0 * 5.0)" might make more sense, or "(double) (+4 * 5)". But this has me totally puzzled. Why would you write a line of code like this, without assigning the result, and why the heck does the compiler not at least issue a warning?/

    – jamesqf
    4 hours ago






  • 1





    @jamesqf I know that it dosn't make sense, but I want to know why this is possible and for this is sense not needed.

    – Ernest Bredar
    3 hours ago


















17















(int) + 4*5;


Why is this possible? (tried with g++ and gcc.)










share|improve this question









New contributor




Ernest Bredar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





















  • Even this is valid it is not a good idea to do that in a program because yes this is quite disturbing ^^

    – bruno
    6 hours ago








  • 1





    same as (int)-4*5

    – P__J__
    5 hours ago











  • Though "(int) (+4.0 * 5.0)" might make more sense, or "(double) (+4 * 5)". But this has me totally puzzled. Why would you write a line of code like this, without assigning the result, and why the heck does the compiler not at least issue a warning?/

    – jamesqf
    4 hours ago






  • 1





    @jamesqf I know that it dosn't make sense, but I want to know why this is possible and for this is sense not needed.

    – Ernest Bredar
    3 hours ago














17












17








17








(int) + 4*5;


Why is this possible? (tried with g++ and gcc.)










share|improve this question









New contributor




Ernest Bredar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












(int) + 4*5;


Why is this possible? (tried with g++ and gcc.)







c++ c casting language-lawyer






share|improve this question









New contributor




Ernest Bredar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




Ernest Bredar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question








edited 9 mins ago









Davislor

9,10511227




9,10511227






New contributor




Ernest Bredar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 6 hours ago









Ernest BredarErnest Bredar

1005




1005




New contributor




Ernest Bredar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Ernest Bredar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Ernest Bredar is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.













  • Even this is valid it is not a good idea to do that in a program because yes this is quite disturbing ^^

    – bruno
    6 hours ago








  • 1





    same as (int)-4*5

    – P__J__
    5 hours ago











  • Though "(int) (+4.0 * 5.0)" might make more sense, or "(double) (+4 * 5)". But this has me totally puzzled. Why would you write a line of code like this, without assigning the result, and why the heck does the compiler not at least issue a warning?/

    – jamesqf
    4 hours ago






  • 1





    @jamesqf I know that it dosn't make sense, but I want to know why this is possible and for this is sense not needed.

    – Ernest Bredar
    3 hours ago



















  • Even this is valid it is not a good idea to do that in a program because yes this is quite disturbing ^^

    – bruno
    6 hours ago








  • 1





    same as (int)-4*5

    – P__J__
    5 hours ago











  • Though "(int) (+4.0 * 5.0)" might make more sense, or "(double) (+4 * 5)". But this has me totally puzzled. Why would you write a line of code like this, without assigning the result, and why the heck does the compiler not at least issue a warning?/

    – jamesqf
    4 hours ago






  • 1





    @jamesqf I know that it dosn't make sense, but I want to know why this is possible and for this is sense not needed.

    – Ernest Bredar
    3 hours ago

















Even this is valid it is not a good idea to do that in a program because yes this is quite disturbing ^^

– bruno
6 hours ago







Even this is valid it is not a good idea to do that in a program because yes this is quite disturbing ^^

– bruno
6 hours ago






1




1





same as (int)-4*5

– P__J__
5 hours ago





same as (int)-4*5

– P__J__
5 hours ago













Though "(int) (+4.0 * 5.0)" might make more sense, or "(double) (+4 * 5)". But this has me totally puzzled. Why would you write a line of code like this, without assigning the result, and why the heck does the compiler not at least issue a warning?/

– jamesqf
4 hours ago





Though "(int) (+4.0 * 5.0)" might make more sense, or "(double) (+4 * 5)". But this has me totally puzzled. Why would you write a line of code like this, without assigning the result, and why the heck does the compiler not at least issue a warning?/

– jamesqf
4 hours ago




1




1





@jamesqf I know that it dosn't make sense, but I want to know why this is possible and for this is sense not needed.

– Ernest Bredar
3 hours ago





@jamesqf I know that it dosn't make sense, but I want to know why this is possible and for this is sense not needed.

– Ernest Bredar
3 hours ago












2 Answers
2






active

oldest

votes


















29














The + here is unary + operator, not the binary addition operator. There's no addition happening here.



Also, the syntax (int) is used for typecasting.



You can re-read that statement as



(int) (+ 4) * 5;    


which is parsed as



((int) (+ 4)) * (5);    


which says,




  • Make the operand +4

  • typecasted to an int

  • multiply with operand 5


This is similar to (int) (- 4) * (5);, where the usage of the unary operator is more familiar.



In your case, the unary + and the cast to int - both are redundant.






share|improve this answer

































    20














    This is interpreted as ((int)(+4)) * 5. That is, an expression +4 (a unary plus operator applied to a literal 4), cast to type int with a C-style cast, and the result multiplied by 5.






    share|improve this answer
























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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      29














      The + here is unary + operator, not the binary addition operator. There's no addition happening here.



      Also, the syntax (int) is used for typecasting.



      You can re-read that statement as



      (int) (+ 4) * 5;    


      which is parsed as



      ((int) (+ 4)) * (5);    


      which says,




      • Make the operand +4

      • typecasted to an int

      • multiply with operand 5


      This is similar to (int) (- 4) * (5);, where the usage of the unary operator is more familiar.



      In your case, the unary + and the cast to int - both are redundant.






      share|improve this answer






























        29














        The + here is unary + operator, not the binary addition operator. There's no addition happening here.



        Also, the syntax (int) is used for typecasting.



        You can re-read that statement as



        (int) (+ 4) * 5;    


        which is parsed as



        ((int) (+ 4)) * (5);    


        which says,




        • Make the operand +4

        • typecasted to an int

        • multiply with operand 5


        This is similar to (int) (- 4) * (5);, where the usage of the unary operator is more familiar.



        In your case, the unary + and the cast to int - both are redundant.






        share|improve this answer




























          29












          29








          29







          The + here is unary + operator, not the binary addition operator. There's no addition happening here.



          Also, the syntax (int) is used for typecasting.



          You can re-read that statement as



          (int) (+ 4) * 5;    


          which is parsed as



          ((int) (+ 4)) * (5);    


          which says,




          • Make the operand +4

          • typecasted to an int

          • multiply with operand 5


          This is similar to (int) (- 4) * (5);, where the usage of the unary operator is more familiar.



          In your case, the unary + and the cast to int - both are redundant.






          share|improve this answer















          The + here is unary + operator, not the binary addition operator. There's no addition happening here.



          Also, the syntax (int) is used for typecasting.



          You can re-read that statement as



          (int) (+ 4) * 5;    


          which is parsed as



          ((int) (+ 4)) * (5);    


          which says,




          • Make the operand +4

          • typecasted to an int

          • multiply with operand 5


          This is similar to (int) (- 4) * (5);, where the usage of the unary operator is more familiar.



          In your case, the unary + and the cast to int - both are redundant.







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited 3 hours ago









          Dancrumb

          18.2k448103




          18.2k448103










          answered 6 hours ago









          Sourav GhoshSourav Ghosh

          112k15136194




          112k15136194

























              20














              This is interpreted as ((int)(+4)) * 5. That is, an expression +4 (a unary plus operator applied to a literal 4), cast to type int with a C-style cast, and the result multiplied by 5.






              share|improve this answer




























                20














                This is interpreted as ((int)(+4)) * 5. That is, an expression +4 (a unary plus operator applied to a literal 4), cast to type int with a C-style cast, and the result multiplied by 5.






                share|improve this answer


























                  20












                  20








                  20







                  This is interpreted as ((int)(+4)) * 5. That is, an expression +4 (a unary plus operator applied to a literal 4), cast to type int with a C-style cast, and the result multiplied by 5.






                  share|improve this answer













                  This is interpreted as ((int)(+4)) * 5. That is, an expression +4 (a unary plus operator applied to a literal 4), cast to type int with a C-style cast, and the result multiplied by 5.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered 6 hours ago









                  Igor TandetnikIgor Tandetnik

                  33.4k33559




                  33.4k33559






















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