c# - JavaScript regex construction -

to test mathematical operator (*, /, +, -) exists in following items:

13*4 7+8 -15/3 7-5 

i have following regex javascript:

/[\*\+/\-]/ 

the problem regex identify negative sign in -15/3 operator. how make not match on first character in string?

you can match regex this:

one or more digits (also allowing decimal) followed optional whitespace  followed operator  followed optional whitespace  followed 1 or more digits (also allowing decimal) 

and reference captured group in middle operator:

/[\d.]+\s*([*+\-\/])\s*[\d.]+/ 

sample code:

var match = str.match(/[\d.]+\s*([*+\-\/])\s*[\d.]+/); if (match) {     var operator = match[1]; } 

working demo , test code: http://jsfiddle.net/jfriend00/dgrsg/

---

if want allow more digits before operators (such other expressions), have lot more simple or complex regex. answer assumes you're trying solve examples you've presented.