Optimize `CheckNumericOnly`

[Saibamen]

Benchmark:

BenchmarkDotNet v0.13.12, Windows 10 (10.0.19045.3996/22H2/2022Update)
Intel Core i7-7820HQ CPU 2.90GHz (Kaby Lake), 1 CPU, 8 logical and 4 physical cores
.NET SDK 8.0.101
  [Host]               : .NET 8.0.1 (8.0.123.58001), X64 RyuJIT AVX2
  .NET 6.0             : .NET 6.0.26 (6.0.2623.60508), X64 RyuJIT AVX2
  .NET 8.0             : .NET 8.0.1 (8.0.123.58001), X64 RyuJIT AVX2
  .NET Framework 4.8.1 : .NET Framework 4.8.1 (4.8.9195.0), X64 RyuJIT VectorSize=256

Method	Runtime	Data	Mean	Error	StdDev	Ratio	RatioSD	Allocated	Alloc Ratio
For	.NET 6.0	1633782928459	13.825 ns	0.1971 ns	0.1747 ns	baseline	****	-	NA
Foreach	.NET 6.0	1633782928459	9.508 ns	0.2147 ns	0.2205 ns	1.45x faster	0.04x	-	NA
For	.NET 8.0	1633782928459	8.053 ns	0.1646 ns	0.1459 ns	baseline		-	NA
Foreach	.NET 8.0	1633782928459	6.731 ns	0.1699 ns	0.3149 ns	1.19x faster	0.07x	-	NA
For	.NET Framework 4.8.1	1633782928459	12.746 ns	0.2686 ns	0.2381 ns	baseline		-	NA
Foreach	.NET Framework 4.8.1	1633782928459	9.324 ns	0.2230 ns	0.3338 ns	1.36x faster	0.07x	-	NA
For	.NET 6.0	NoNumericHere	13.085 ns	0.2023 ns	0.1793 ns	baseline	****	-	NA
Foreach	.NET 6.0	NoNumericHere	9.949 ns	0.2733 ns	0.7885 ns	1.37x faster	0.12x	-	NA
For	.NET 8.0	NoNumericHere	8.901 ns	0.2812 ns	0.8157 ns	baseline		-	NA
Foreach	.NET 8.0	NoNumericHere	7.729 ns	0.2350 ns	0.6856 ns	1.16x faster	0.13x	-	NA
For	.NET Framework 4.8.1	NoNumericHere	12.945 ns	0.1764 ns	0.1563 ns	baseline		-	NA
Foreach	.NET Framework 4.8.1	NoNumericHere	9.813 ns	0.2633 ns	0.7682 ns	1.36x faster	0.08x	-	NA
For	.NET 6.0	Numeric56Text	14.553 ns	0.3292 ns	0.8900 ns	baseline	****	-	NA
Foreach	.NET 6.0	Numeric56Text	9.687 ns	0.2278 ns	0.2961 ns	1.52x faster	0.09x	-	NA
For	.NET 8.0	Numeric56Text	8.759 ns	0.2091 ns	0.2719 ns	baseline		-	NA
Foreach	.NET 8.0	Numeric56Text	7.009 ns	0.1694 ns	0.1883 ns	1.25x faster	0.05x	-	NA
For	.NET Framework 4.8.1	Numeric56Text	13.821 ns	0.3142 ns	0.5249 ns	baseline		-	NA
Foreach	.NET Framework 4.8.1	Numeric56Text	9.750 ns	0.2284 ns	0.4346 ns	1.42x faster	0.09x	-	NA

Code

```cs using BenchmarkDotNet.Attributes; using BenchmarkDotNet.Jobs; namespace BenchmarkTemplate; [MemoryDiagnoser] [Config(typeof(StyleConfig))] [HideColumns("Job")] [SimpleJob(RuntimeMoniker.Net481)] [SimpleJob(RuntimeMoniker.Net60)] [SimpleJob(RuntimeMoniker.Net80)] public class CheckNumericOnlyBenchmarks { [Params("Numeric56Text", "NoNumericHere", "1633782928459")] public string Data; [Benchmark(Baseline = true)] public bool For() { char c; for (int i = 0; i < Data.Length; i++) { c = Data[i]; if (c < '0' && c > '9') { return false; } } return true; } [Benchmark] public bool Foreach() { foreach (var c in Data) { if (c < '0' && c > '9') { return false; } } return true; } } ```

[barnhill]

Nice!!!