正则表达式检查某些字符和数字模式

Question

I have users inputting a file in the format of

image[1-4 digits][0-1 alphabet]

for eg : (valid names)

image1
image1f
image1B
image2201
image2201a

non valid

image (no number specified)
imagez (no number specified)
image12a1 (no digit permitted after letter)
image44aa (only one letter allowed after number)

how can i check if the right format has been entered ?

Answer 1

Not sure if you want php or javascript. Here is the JS version:

/^image(\d{1,4})([A-Za-z])?$/

To extract the number:

var result = regex.exec(tests[i]),
    isValid = result !== null,
    number = isValid && result[1],
    lastChar = isValid && result[2];

Check out the updated example: http://jsfiddle.net/Ug7XD/2/

Answer 2

This should help you...

/^image[0-9]{1,4}[a-zA-Z]{0,1}$/

Here is explained. ^ means start of a string, image well the string, [0-9] is used to identify number from 0 to 9, {1,4} means that numbers must be 1 or 4 times, then [a-zA-Z] checks for characters, and {0,1} checks if there is a 1 character after digit or none, and $ means the end of the string you supply in variable. The / is used to escape the regex string.

Answer 3

尝试

$pattern = "/^image\d{1,4}[A-Za-z]$/";