#include <iostream.h>
void main()
{
int d;
int i=0,n,j,b[100];
cout<<"\n Press 1 for Decimal to Binary converstion";
cout<<"\n press 2 for Decimal to Octal converstion ";
cout<<"\n press 3 for Decimal to Hexadecimal converstion";
cout<<"\n\nEnter your choice: ";
cin>>d;
switch(d)
{
case 1:
cout<<"\nEnter decimal number: ";
cin>>n;
while (n>0)
{
b[i]=n%2;
n=n/2;
i++;
}
cout<<"\nBinary is: ";
j=i-1;
for (i=j;j>=0;j--)
{
cout<<b[j];
}
break;
case 2:
cout<<"\nEnter decimal number: ";
cin>>n;
while (n>0)
{
b[i]=n%8;
n=n/8;
i++;
}
cout<<"\nOctal is: ";
j=i-1;
for (i=j;j>=0;j--)
{
cout<<b[j];
}

break;
case 3:
cout<<"\nEnter decimal number: ";
cin>>n;
while (n>0)
{
b[i]=n%16;
n=n/16;
i++;
}
cout<<"\nHexadecimal is:";
j=i-1;
for (i=j;j>=0;j--)
{
cout<<b[j];
if(b[j]<10)
{
cout<<b[j];
}
else
{
switch(b[j])
{
case 10:
cout<<"A";
break;
case 11:
cout<<"B";
break;
case 12:
cout<<"C";
break;
case 13:
cout<<"D";
break;
case 14:
cout<<"E";
break;
case 15:
cout<<"F";
break;
}
}
}

}

}

it produces the following error "main must retrun int"please see what is the problem iam using code blocks 8 with mingw

Try this:

#include <iostream.h>
int main()
{
int d;
int i=0,n,j,b[100];
cout<<"\n Press 1 for Decimal to Binary converstion";
cout<<"\n press 2 for Decimal to Octal converstion ";
cout<<"\n press 3 for Decimal to Hexadecimal converstion";
cout<<"\n\nEnter your choice: ";
cin>>d;
switch(d)
{
case 1:
cout<<"\nEnter decimal number: ";
cin>>n;
while (n>0)
{
b[i]=n%2;
n=n/2;
i++;
}
cout<<"\nBinary is: ";
j=i-1;
for (i=j;j>=0;j--)
{
cout<<b[j];
}
break;
case 2:
cout<<"\nEnter decimal number: ";
cin>>n;
while (n>0)
{
b[i]=n%8;
n=n/8;
i++;
}
cout<<"\nOctal is: ";
j=i-1;
for (i=j;j>=0;j--)
{
cout<<b[j];
}

break;
case 3:
cout<<"\nEnter decimal number: ";
cin>>n;
while (n>0)
{
b[i]=n%16;
n=n/16;
i++;
}
cout<<"\nHexadecimal is:";
j=i-1;
for (i=j;j>=0;j--)
{
cout<<b[j];
if(b[j]<10)
{
cout<<b[j];
}
else
{
switch(b[j])
{
case 10:
cout<<"A";
break;
case 11:
cout<<"B";
break;
case 12:
cout<<"C";
break;
case 13:
cout<<"D";
break;
case 14:
cout<<"E";
break;
case 15:
cout<<"F";
break;
}
}
}

}

}

Indent your code, it's really messy!!

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