Identifier not found error on function call

Question

I have a program here where I invert the case of an entered string  This is the code in my  cpp file and I am using Visual Studio C   IDE  I am not sure what I need in a header file or if I need one to make this work   Error with my function call swapCase  Main does not see swapCase for some reason that I m not sure of    include  lt cctype gt   include  lt iostream gt   include  lt conio h gt   using namespace std   int main         char name 30       cout lt  lt  Enter a name         cin getline name  30       swapCase name       cout lt  lt  Changed case is    lt  lt  name  lt  lt endl       getch        return 0     void swapCase  char  name        for int i 0 name i  i                  if   name i   gt    A   amp  amp  name i   lt    Z                name i     32    changing upper to lower         else if  name i   gt    a   amp  amp  name i   lt    z               name i  -  32    changing lower to upper           Any other tips for syntax or semantics is appreciated

User · Answer

Unlike other languages you may be used to, everything in C++ has to be declared before it can be used. The compiler will read your source file from top to bottom, so when it gets to the call to swapCase, it doesn't know what it is so you get an error. You can declare your function ahead of main with a line like this:

void swapCase(char *name);

or you can simply move the entirety of that function ahead of main in the file. Don't worry about having the seemingly most important function (main) at the bottom of the file. It is very common in C or C++ to do that.

User · Answer

At the time the compiler encounters the call to swapCase in main    it does not know about the function swapCase  so it reports an error   You can either move the definition of swapCase above main  or declare swap case above main   void swapCase char  name     Also  the 32 in swapCase causes the reader to pause and wonder   The comment helps   In this context  it would add clarity to write  if   A   lt   name i   amp  amp  name i   lt    Z       name i      a  -  A   else if   a   lt   name i   amp  amp  name i   lt    z       name i      A  -  a     The construction in my if-tests is a matter of personal style   Yours were just fine   The main thing is the way to modify name i  -- using the difference in  a  vs   A  makes it more obvious what is going on  and nobody has to wonder if the  32  is actually correct   Good luck learning

User · Answer

You have to define void swapCase before the main definition

User · Answer

Add this line before main function   void swapCase  char  name    int main               swapCase name         swapCase prototype should be known at this point            This is called forward declaration  compiler needs to know function prototype when function call is compiled

[c++] Identifier not found error on function call

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