end of day 4 week 1

week 1/day 4/exo3.ps1

@@ -0,0 +1,28 @@
+# accept the username only if
+# it contain letters, the username is inferior at 20
+# start with a letter, no digit, no space
+
+$username = Read-Host("Please enter your username");
+$badChar = $false;
+
+if($username -eq ''){
+    Write-Host("The username can't be empty");
+    exit;
+}
+
+foreach($char in $username.ToCharArray()){
+    if($char -notmatch '[A-Za-z]' -or $char -eq ' '){
+        $badChar = $true;
+        break
+    }
+}
+
+$firstLetter = $username[0]
+$validFirstLetter = $firstLetter -match '[A-Za-z]'
+
+if(-not $badChar  -and $username.Length -le 20  -and $validFirstLetter ){
+    Write-Host("Accepted");
+}else{
+    Write-Host("Invalid");
+
+}