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Structures

ABDUL HAYEEABDUL HAYEE Posts: 81Member
Dear Sir,
Placed below is a part of a small program on structures. The structure < MyString >
defines an array . and a pointer.

The comilaer is giveing three errors , the first one is that C++ forbids declaration without a data type . Please refer ther comiler log - 1.
Although both the elements have been defined within the struct < MyString > . This anomoly is not understanable.

Secondly , when datatype MyStructure was placed in front on line 23 , the the compiler indicates that declaration already made at line 21 .

Could you please explain the anomoly and provide the remedy.
Thanking you.
/* 786 */
/* ***** Structures ***** */


#include
#include
#include

using namespace std ;


struct MyStructure
{
char MyString [40] ; // String of max 40 chracters
int MyInteger ; // const variable

} ;
MyStructure StructureVariable [20] ; // An array of 20 elements
MyStructure * StructurePointer ; // a pointer --- Line 21

StructurePointer = StructureVariable ; // Line - 23


int main ()
{
cout<<endl<<endl ;
cout<<endl<<endl ;
cout <<" " ;

cout << " My String ! : << endl<<endl ;
system ("pause") ;
return 0 ;
}




---------------------------------------------------------------------
/* COMPILE LOG - 1 */

Compiler: Default compiler
Executing g++.exe...
g++.exe "F:Dev-CppStructures.cpp" -o "F:Dev-CppStructures.exe" -I"F:Dev-Cppincludec++3.3.1ackward" -I"F:Dev-Cppincludec++3.3.1mingw32" -I"F:Dev-Cppincludec++3.3.1" -I"F:Dev-Cppinclude" -L"F:Dev-Cpplib"
F:/Dev-Cpp/Structures.cpp:23: error: ISO C++ forbids declaration of `
StructurePointer' with no type
F:/Dev-Cpp/Structures.cpp:23: error: conflicting types for `int
StructurePointer'
F:/Dev-Cpp/Structures.cpp:21: error: previous declaration as `
MyStructure*StructurePointer'

Execution terminated

-------------------------------------------------------------------
/* COMPILE LOG - 2 */


Compiler: Default compiler
Executing g++.exe...
g++.exe "F:Dev-CppStructures.cpp" -o "F:Dev-CppStructures.exe" -I"F:Dev-Cppincludec++3.3.1ackward" -I"F:Dev-Cppincludec++3.3.1mingw32" -I"F:Dev-Cppincludec++3.3.1" -I"F:Dev-Cppinclude" -L"F:Dev-Cpplib"
F:/Dev-Cpp/Structures.cpp:23: error: conflicting types for `MyStructure
StructurePointer'

F:/Dev-Cpp/Structures.cpp:21: error: previous declaration as `

MyStructure*StructurePointer'

Execution terminated



Comments

  • HK_MP5KPDWHK_MP5KPDW Posts: 770Member ✭✭✭
    : Dear Sir,
    : Placed below is a part of a small program on structures. The structure < MyString >
    : defines an array . and a pointer.
    :
    : The comilaer is giveing three errors , the first one is that C++ forbids declaration without a data type . Please refer ther comiler log - 1.
    : Although both the elements have been defined within the struct < MyString > . This anomoly is not understanable.
    :
    : Secondly , when datatype MyStructure was placed in front on line 23 , the the compiler indicates that declaration already made at line 21 .
    :
    : Could you please explain the anomoly and provide the remedy.
    : Thanking you.

    [blue]Please use code tags when posting code samples, for example:[/blue]

    [code]
    /* 786 */
    /* ***** Structures ***** */

    #include
    #include
    #include

    using namespace std ;


    struct MyStructure
    {
    char MyString [40] ; // String of max 40 chracters
    int MyInteger ; // const variable
    } ;

    MyStructure StructureVariable [20] ; // An array of 20 elements
    MyStructure * StructurePointer ; // a pointer --- Line 21

    [red]StructurePointer = StructureVariable ; // Line - 23 [/red]


    int main ()
    {
    cout<<endl<<endl ;
    cout<<endl<<endl ;
    cout <<" " ;

    cout << " My String ! : << endl<<endl ;
    system ("pause") ;
    return 0 ;
    }
    [/code]

    [blue]
    The line in [red]red[/red] above isn't legal, you can have a declaration statment of a variable and initialize it as a single code statement, but you can't have a seperate initialization step outside of a block of code in a function.

    Illegal:
    [code]MyStructure * StructurePointer ;

    [red]// Can't have a seperate initialization statement outside of a block of code in some function
    StructurePointer = StructureVariable ;[/red][/code]

    Legal:
    [code]// This is legal since it is a single combined declaration/initialization statement
    MyStructure * StructurePointer = StructureVariable ;[/code]

    Other than that, the [italic]stdlib.h[/italic] header should be replaced with [italic]cstdlib[/italic] instead.[/blue]



    :
    : ---------------------------------------------------------------------
    : /* COMPILE LOG - 1 */
    :
    : Compiler: Default compiler
    : Executing g++.exe...
    : g++.exe "F:Dev-CppStructures.cpp" -o "F:Dev-CppStructures.exe" -I"F:Dev-Cppincludec++3.3.1ackward" -I"F:Dev-Cppincludec++3.3.1mingw32" -I"F:Dev-Cppincludec++3.3.1" -I"F:Dev-Cppinclude" -L"F:Dev-Cpplib"
    : F:/Dev-Cpp/Structures.cpp:23: error: ISO C++ forbids declaration of `
    : StructurePointer' with no type
    : F:/Dev-Cpp/Structures.cpp:23: error: conflicting types for `int
    : StructurePointer'
    : F:/Dev-Cpp/Structures.cpp:21: error: previous declaration as `
    : MyStructure*StructurePointer'
    :
    : Execution terminated
    :
    : -------------------------------------------------------------------
    : /* COMPILE LOG - 2 */
    :
    :
    : Compiler: Default compiler
    : Executing g++.exe...
    : g++.exe "F:Dev-CppStructures.cpp" -o "F:Dev-CppStructures.exe" -I"F:Dev-Cppincludec++3.3.1ackward" -I"F:Dev-Cppincludec++3.3.1mingw32" -I"F:Dev-Cppincludec++3.3.1" -I"F:Dev-Cppinclude" -L"F:Dev-Cpplib"
    : F:/Dev-Cpp/Structures.cpp:23: error: conflicting types for `MyStructure
    : StructurePointer'
    :
    : F:/Dev-Cpp/Structures.cpp:21: error: previous declaration as `
    :
    : MyStructure*StructurePointer'
    :
    : Execution terminated
    :
    :
    :
    :

  • ABDUL HAYEEABDUL HAYEE Posts: 81Member
    : : Dear Sir,
    : : Placed below is a part of a small program on structures. The structure < MyString >
    : : defines an array . and a pointer.
    : :
    : : The comilaer is giveing three errors , the first one is that C++ forbids declaration without a data type . Please refer ther comiler log - 1.
    : : Although both the elements have been defined within the struct < MyString > . This anomoly is not understanable.
    : :
    : : Secondly , when datatype MyStructure was placed in front on line 23 , the the compiler indicates that declaration already made at line 21 .
    : :
    : : Could you please explain the anomoly and provide the remedy.
    : : Thanking you.
    :
    : [blue]Please use code tags when posting code samples, for example:[/blue]
    :
    : [code]
    : /* 786 */
    : /* ***** Structures ***** */
    :
    : #include
    : #include
    : #include
    :
    : using namespace std ;
    :
    :
    : struct MyStructure
    : {
    : char MyString [40] ; // String of max 40 chracters
    : int MyInteger ; // const variable
    : } ;
    :
    : MyStructure StructureVariable [20] ; // An array of 20 elements
    : MyStructure * StructurePointer ; // a pointer --- Line 21
    :
    : [red]StructurePointer = StructureVariable ; // Line - 23 [/red]
    :
    :
    : int main ()
    : {
    : cout<<endl<<endl ;
    : cout<<endl<<endl ;
    : cout <<" " ;
    :
    : cout << " My String ! : << endl<<endl ;
    : system ("pause") ;
    : return 0 ;
    : }
    : [/code]
    :
    : [blue]
    : The line in [red]red[/red] above isn't legal, you can have a declaration statment of a variable and initialize it as a single code statement, but you can't have a seperate initialization step outside of a block of code in a function.
    :
    : Illegal:
    : [code]MyStructure * StructurePointer ;
    :
    : [red]// Can't have a seperate initialization statement outside of a block of code in some function
    : StructurePointer = StructureVariable ;[/red][/code]
    :
    : Legal:
    : [code]// This is legal since it is a single combined declaration/initialization statement
    : MyStructure * StructurePointer = StructureVariable ;[/code]
    :
    : Other than that, the [italic]stdlib.h[/italic] header should be replaced with [italic]cstdlib[/italic] instead.[/blue]
    :
    :

    [code][green]
    Dear Sir,
    I am thankful for the reply ,
    I implied it , and the first error was rectified.
    Now the excution ( rather compilation ) is generating dual declaration error , as mentioned in Compiler log - 2 below. I could not find the method to remove this fault. Plz help.
    Thanks, [/green ] [/code]

    .......................................................................











    :
    : :
    : : ---------------------------------------------------------------------
    : : /* COMPILE LOG - 1 */
    : :
    : : Compiler: Default compiler
    : : Executing g++.exe...
    : : g++.exe "F:Dev-CppStructures.cpp" -o "F:Dev-CppStructures.exe" -I"F:Dev-Cppincludec++3.3.1ackward" -I"F:Dev-Cppincludec++3.3.1mingw32" -I"F:Dev-Cppincludec++3.3.1" -I"F:Dev-Cppinclude" -L"F:Dev-Cpplib"
    : : F:/Dev-Cpp/Structures.cpp:23: error: ISO C++ forbids declaration of `
    : : StructurePointer' with no type
    : : F:/Dev-Cpp/Structures.cpp:23: error: conflicting types for `int
    : : StructurePointer'
    : : F:/Dev-Cpp/Structures.cpp:21: error: previous declaration as `
    : : MyStructure*StructurePointer'
    : :
    : : Execution terminated
    : :
    : : -------------------------------------------------------------------
    : : /* COMPILE LOG - 2 */
    : :
    : :
    : : Compiler: Default compiler
    : : Executing g++.exe...
    : : g++.exe "F:Dev-CppStructures.cpp" -o "F:Dev-CppStructures.exe" -I"F:Dev-Cppincludec++3.3.1ackward" -I"F:Dev-Cppincludec++3.3.1mingw32" -I"F:Dev-Cppincludec++3.3.1" -I"F:Dev-Cppinclude" -L"F:Dev-Cpplib"
    : : F:/Dev-Cpp/Structures.cpp:23: error: conflicting types for `MyStructure
    : : StructurePointer'
    : :
    : : F:/Dev-Cpp/Structures.cpp:21: error: previous declaration as `
    : :
    : : MyStructure*StructurePointer'
    : :
    : : Execution terminated
    : :
    : :
    : :
    : :
    :
    :

  • LundinLundin Posts: 3,711Member
    I don't get any errors when compiling the code in Dev.
    Post the modified code.
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