正則表達式應用范例（轉）
2024-07-21 02:20:22
供稿：網友
the following example shows the use of regular expresssions in c#.this program has basic validation scripts for validation easily useable in all programs.
/*
<howtocompile>
csc /r:system.text.regularexpressions.dll,system.dll validation.cs
</howtocomplie>
*/
using system.text.regularexpressions;
using system;
class validation
{
public static void main()
{
string strtotest;
validation objvalidate=new validation();
console.write("enter a string to test for alphabets:");
strtotest=console.readline();
if(objvalidate.isalpha(strtotest))
{
console.writeline("{0} is valid alpha string",strtotest);
}
else
{
console.writeline("{0} is not a valid alpha string",strtotest);
}
}
// function to test for positive integers.
public bool isnaturalnumber(string strnumber)
{
regex objnotnaturalpattern=new regex("[^0-9]");
regex objnaturalpattern=new regex("0*[1-9][0-9]*");
return !objnotnaturalpattern.ismatch(strnumber) &&
objnaturalpattern.ismatch(strnumber);
}
// function to test for positive integers with zero inclusive
public bool iswholenumber(string strnumber)
{
regex objnotwholepattern=new regex("[^0-9]");
return !objnotwholepattern.ismatch(strnumber);
}
// function to test for integers both positive & negative
public bool isinteger(string strnumber)
{
regex objnotintpattern=new regex("[^0-9-]");
regex objintpattern=new regex("^-[0-9]+$|^[0-9]+$");
return !objnotintpattern.ismatch(strnumber) &&
objintpattern.ismatch(strnumber);
}
// function to test for positive number both integer & real
public bool ispositivenumber(string strnumber)
{
regex objnotpositivepattern=new regex("[^0-9.]");
regex objpositivepattern=new regex("^[.][0-9]+$|[0-9]*[.]*[0-9]+$");
regex objtwodotpattern=new regex("[0-9]*[.][0-9]*[.][0-9]*");
return !objnotpositivepattern.ismatch(strnumber) &&
objpositivepattern.ismatch(strnumber) &&
!objtwodotpattern.ismatch(strnumber);
}
// function to test whether the string is valid number or not
public bool isnumber(string strnumber)
{
regex objnotnumberpattern=new regex("[^0-9.-]");
regex objtwodotpattern=new regex("[0-9]*[.][0-9]*[.][0-9]*");
regex objtwominuspattern=new regex("[0-9]*[-][0-9]*[-][0-9]*");
string strvalidrealpattern="^([-]|[.]|[-.]|[0-9])[0-9]*[.]*[0-9]+$";
string strvalidintegerpattern="^([-]|[0-9])[0-9]*$";
regex objnumberpattern =new regex("(" + strvalidrealpattern +")|(" + strvalidintegerpattern + ")");
return !objnotnumberpattern.ismatch(strnumber) &&
!objtwodotpattern.ismatch(strnumber) &&
!objtwominuspattern.ismatch(strnumber) &&
objnumberpattern.ismatch(strnumber);
}
// function to test for alphabets.
public bool isalpha(string strtocheck)
{
regex objalphapattern=new regex("[^a-za-z]");
return !objalphapattern.ismatch(strtocheck);
}
// function to check for alphanumeric.
public bool isalphanumeric(string strtocheck)
{
regex objalphanumericpattern=new regex("[^a-za-z0-9]");
return !objalphanumericpattern.ismatch(strtocheck);
}
}
there is another simple way to perform these validation think of it while the next article comes.
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