Looking for C# equivalent of scanf

Question

I used to code in C language in the past and I found the scanf function very useful. Unfortunately, there is no equivalent in C#.

I am using using it to

Answer 1

Try importing msvcrt.dll

using System.Runtime.InteropServices;

namespace Sample
{
    class Program
    {
        [DllImport("msvcrt.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern int printf(string format, __arglist);

        [DllImport("msvcrt.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern int scanf(string format, __arglist);

        static void Main()
        {
            int a, b;
            scanf("%d%d", __arglist(out a, out b));
            printf("The sum of %d and %d is %d.\n", __arglist(a, b, a + b));
        }
    }
}

which works well on .NET Framework. But on Mono, it shows the error message:

Unhandled Exception:
System.InvalidProgramException: Invalid IL code in Sample.Program:Main (): IL_0009: call      0x0a000001


[ERROR] FATAL UNHANDLED EXCEPTION: System.InvalidProgramException: Invalid IL code in Sample.Program:Main (): IL_0009: call      0x0a000001

If you need Mono compatibility, you need to avoid using arglist

using System.Runtime.InteropServices;

namespace Sample
{
    class Program
    {
        [DllImport("msvcrt.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern int printf(string format, int a, int b, int c);

        [DllImport("msvcrt.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern int scanf(string format, out int a, out int b);

        static void Main()
        {
            int a, b;
            scanf("%d%d", out a, out b);
            printf("The sum of %d and %d is %d.\n", a, b, a + b);
        }
    }
}

in which the number of arguments is fixed.

Edit 2018-5-24

arglist doesn't work on .NET Core either. It seems that calling the C vararg function is deprecated. You should use the .NET string API such as String.Format instead.