invalid conversion from const char to char

Question

Have a code as shown below  I have problem passing the arguments   stringstream data  char  addr NULL  strcpy addr retstring   c str       retstring   is a function that returns a string     more code printfunc num addr data str   c str       I get the error      invalid conversion from  const char   to  char         initializing argument 3 of  void Printfunc int  char   char   on argument 3 of the function   on the above line  The function is called as shown below  void Printfunc int a  char  loc  char  stream    please  let me know if I need to change any initialization

User · Answer

First of all this code snippet  char  addr NULL  strcpy addr retstring   c str       is invalid because you did not allocate memory where you are going to copy retstring   c str     As for the error message then it is clear enough  The type of expression data str   c str   is const char   but the third parameter of the function is declared as char    You may not assign an object of type const char   to an object of type char    Either the function should define the third parameter as const char   if it does not change the object pointed by the third parameter or you may not pass argument of type const char

User · Answer

string  c str   returns a string of type const char   as seen here  A quick fix  try casting printfunc num addr  char   data str   c str      While the above may work  it is undefined behaviour  and unsafe   Here s a nicer solution using templates   char   my argument   const cast lt char  gt       c str

User · Answer

Well  data str   c str   yields a char const  but your function Printfunc   wants to have char s  Based on the name  it doesn t change the arguments but merely prints them and or uses them to name a file  in which case you should probably fix your declaration to be  void Printfunc int a  char const  loc  char const  stream    The alternative might be to turn the char const  into a char  but fixing the declaration is preferable   Printfunc num  addr  const cast lt char  gt  data str   c str

[c++] invalid conversion from 'const char' to 'char'

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[c++] invalid conversion from 'const char' to 'char'