IsNumber

Bool IsNumber (
string str) {
    
return (str.Replace (
"0", 
"").Replace (
"1", 
"").Replace (
"2", 
"").Replace (
"3", 
"").Replace (
"4", 
"").Replace (
"5", 
"").Replace (
"6", 
"").Replace (
"7", 
"").Replace (
"8", 
"").Replace (
"9", 
"").Length == 0);
}