c# – Reversely print string

Question:

Why can't I print this string in reverse? I know there is a possibility of using another simpler way, but I want to understand the error.

static void Main(string[] args)
{
     string frase = "Diego lima de Aquino";

     for(int i = frase.Length; i>=0; i--)
     {
         Console.WriteLine(frase[i]);
     }

     Console.ReadKey();
}

Mistake:

System.IndexOutOfRangeException was unhandled
HResult=-2146233080
Message=Index was outside the bounds of the array.
Source=mscorlib
StackTrace:
    at System.String.get_Chars(Int32 index)
    at AppNoPrompt_1.Program.Main(String[] args) in C:\Users\Diegolaquino\documents\visual studio 2015\Projects\AppNoPrompt_1\AppNoPrompt_1\Program.cs:line 20
    at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
    at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
    at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
    at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
    at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
    at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
    at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
    at System.Threading.ThreadHelper.ThreadStart()
InnerException: 

Answer:

The error is in the declaration of the i

int i = frase.Length

Problem

frase.Length returns the number of items in the array.

frase[i] , starts at index 0 .

For example 5 items:

frase.Length == 5
frase[0] até frase[4] // frase[5] só existiria se houvesse 6 elementos

To solve this problem just decrease 1 in the declaration of the i

for(int i = frase.Length - 1; i>=0; i--)
{
     Console.WriteLine(frase[i]);
}

Where

for(int i = frase.Length ; i>=1; i--)
{
     Console.WriteLine(frase[i-1]);
}