c# - how to create a custom cast explicit in c #? -

have code:

string abc = "123456"; 

to convert int should use convert:

int abcint = convert.toint32(abc); 

the problem if not number have exception see returning 0 final code like:

try{ int abcint = convert.toint32(abc); }catch(exception e){ int abcint = 0; } 

so see decided create book made ​​me object returning 0 numeric without exception if failed, keep flexible programming without junk code:

int abcint = libs.str.safeint(abc); 

the code is:

public int safeint(object ob) {     if ((ob == null) || (string.isnullorempty(ob.tostring())))         return 0;     try     {         return convert.toint32(             system.text.regularexpressions.regex.replace(ob.tostring(), @"@[^ee0-9\.\,]+@i", "").             tostring(cultureinfo.invariantculture.numberformat)         );     }     catch (formatexception e)     {         return 0;     } } 

but want go 1 step further , this:

int abcint = (safeint)abc; 

how do?

can not convert type 'string' 'libs.safeint.safeint'

you should use int32.tryparse:

int abcint; if(!int32.tryparse(abc, out abcint)) {     abcint = 0; } // abcint has been parsed int, or defaulted 0 

note can shortened to

int abcint; int32.tryparse(abc, out abcint); 

if want default value 0 because:

when method returns, contains 32-bit signed integer value equivalent number contained in s, if conversion succeeded, or zero if conversion failed. conversion fails if s parameter null, not of correct format, or represents number less minvalue or greater maxvalue. parameter passed uninitialized.

i recommend against writing way because can't distinguish between abc = "0" , abc = "garbage"; both exhibit same behavior above 2 lines of code. initial version above (i.e., if, can distinguish 2 cases if need to; silently ignoring errors generally bad idea).

that said, if absolutely dying know how implement explicit cast operator, proceed this:

class safeint32 {     private readonly int value;     public int value { { return this.value; } }      private readonly string source;     public string source { { return this.source; } }      private readonly bool successful;     public bool successful { { return this.successful; } }      public safeint32(string source) {         this.source = source;         this.successful = int32.tryparse(source, out this.value);     }      public static explicit operator safeint32(string source) {         return new safeint32(source);     }      public static implicit operator int(safeint32 safeint32) {         return safeint32.value;     } } 

usage:

int abcint = (safeint32)"123456"; 

note had define explicit cast operator cast string safeint32, , implicit cast operator cast safeint32 int achieve desired syntax. latter necessary compiler can silently convert result of (safeint32)"123456" int.

again, recommend against this; use int32.tryparse.