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Quantifiers

A quantifier can be appended to a character, a character class, or a [...] set. It specifies how many count of preceding item we need.

Quick Reference
*	0 or more. This is same as `{0,}`.
+	1 or more. This is same as `{1,}`.
?	0 or 1. This is same as `{0, 1}`.
❴2❵	Exactly 2 times
❴2,8❵	Between 2 and 8 times
❴2,❵	2 or more times

1. The quantifiers *, + and ?
Word Wrap
Enter input string
How much wood would a woodchuck chuck if a woodchuck could chuck wood? He would chuck, he would, as much as he could, and chuck as much wood As a woodchuck would if a woodchuck could chuck wood
o*d matches zero or more o followed by a d. Notice here the character d of the word would and could are also matched as they have zero o before it.
o{0,}d is equivalent to this pattern.
Enter regex pattern
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
/o*d/gCount:16
How much wood would a woodchuck chuck if a woodchuck could chuck wood? He would chuck, he would, as much as he could, and chuck as much wood As a woodchuck would if a woodchuck could chuck wood
match position
ood 10
d 18
ood 23
ood 44
d 57
ood 66
d 78
d 94
d 115
d 120
ood 137
ood 147
d 160
ood 168
d 181
ood 190
o+d matches one or more o followed by a d.
o{1,}d is equivalent to this pattern.
Enter regex pattern
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
/o+d/gCount:8
How much wood would a woodchuck chuck if a woodchuck could chuck wood? He would chuck, he would, as much as he could, and chuck as much wood As a woodchuck would if a woodchuck could chuck wood
match position
ood 10
ood 23
ood 44
ood 66
ood 137
ood 147
ood 168
ood 190
o?d matches zero or one o followed by a d. Notice here the first o of the word wood is never matched.
o{0,1}d is equivalent to this pattern.
Enter regex pattern
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
/o?d/gCount:16
How much wood would a woodchuck chuck if a woodchuck could chuck wood? He would chuck, he would, as much as he could, and chuck as much wood As a woodchuck would if a woodchuck could chuck wood
match position
od 11
d 18
od 24
od 45
d 57
od 67
d 78
d 94
d 115
d 120
od 138
od 148
d 160
od 169
d 181
od 191
2. The quantifiers {n}
Word Wrap
Enter input string
2 6 12 34 15334 75 102 800 9 1200 35325 450
\b\d{3}\b matches exact 3-digit integers.
Enter regex pattern
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
/\b\d{3}\b/gCount:3
2 6 12 34 15334 75 102 800 9 1200 35325 450
match position
102 19
800 23
450 40
\b\d{1,3}\b matches digits upto 3 digits.
Note: \b\d{1, 3}\b will not work as there should not be any space after the comma between the numbers.
Enter regex pattern
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
/\b\d{1,3}\b/gCount:9
2 6 12 34 15334 75 102 800 9 1200 35325 450
match position
2 0
6 2
12 4
34 7
75 16
102 19
800 23
9 27
450 40
\b\d{3,}\b matches those integers that are 3 or above number of digits.
Enter regex pattern
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
/\b\d{3,}\b/gCount:6
2 6 12 34 15334 75 102 800 9 1200 35325 450
match position
15334 10
102 19
800 23
1200 29
35325 34
450 40
3. Greedy quantifiers
Word Wrap
By default, the regexp engine tries to repeat the quantifiers * and + as many times as possible. This behavior is called greedy as they try to match as much of the text as possible. The opposite of this behavior is lazy mode.
Let's understand this behavior with an example.
Enter input string
Draw a line graph from (1,6) to (2,4) to (3,2) and finally end at (10,12). Note: The xy coordinates are represented as (x,y). This means (starting point, ending point).
Using quantifiers, let's get the contents present inside the () from the given text.
With the default greedy behavior, the regexp machine tries to match all between the first ( and the last ). This is not what we want.
Enter regex pattern
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
/\(.+\)/gCount:2
Draw a line graph from (1,6) to (2,4) to (3,2) and finally end at (10,12). Note: The xy coordinates are represented as (x,y). This means (starting point, ending point).
match position
(1,6) to (2,4) to (3,2) and finally end at (10,12) 23
(x,y). This means (starting point, ending point) 119
How to turn off the greedy behavior?
Add ? to the quantifier to make it non greedy. This way we get the desired result.
Note: ? is also a quantifier which matches its preceding item zero or once. But if it is added to another quantifier or even itself, it gets a different meaning. It changes from the default greedy to lazy mode. *, + and ? operates in greedy mode. *?, +? and ?? operates in lazy (non greedy) mode.
Enter regex pattern
i - Ignore Case
g - Global Match
m - Multiline
s - Dot All
u - Unicode
y - Sticky
With lastIndex^?
/\(.+?\)/gCount:6
Draw a line graph from (1,6) to (2,4) to (3,2) and finally end at (10,12). Note: The xy coordinates are represented as (x,y). This means (starting point, ending point).
match position
(1,6) 23
(2,4) 32
(3,2) 41
(10,12) 66
(x,y) 119
(starting point, ending point) 137

match	position
ood	10
d	18
ood	23
ood	44
d	57
ood	66
d	78
d	94
d	115
d	120
ood	137
ood	147
d	160
ood	168
d	181
ood	190

match	position
od	11
d	18
od	24
od	45
d	57
od	67
d	78
d	94
d	115
d	120
od	138
od	148
d	160
od	169
d	181
od	191

match	position
(1,6) to (2,4) to (3,2) and finally end at (10,12)	23
(x,y). This means (starting point, ending point)	119

match	position
(1,6)	23
(2,4)	32
(3,2)	41
(10,12)	66
(x,y)	119
(starting point, ending point)	137

match	position
102	19
800	23
450	40

match	position
2	0
6	2
12	4
34	7
75	16
102	19
800	23
9	27
450	40

match	position
15334	10
102	19
800	23
1200	29
35325	34
450	40

match	position
ood	10
d	18
ood	23
ood	44
d	57
ood	66
d	78
d	94
d	115
d	120
ood	137
ood	147
d	160
ood	168
d	181
ood	190

match	position
od	11
d	18
od	24
od	45
d	57
od	67
d	78
d	94
d	115
d	120
od	138
od	148
d	160
od	169
d	181
od	191

How to turn off the greedy behavior?

match	position
ood	10
d	18
ood	23
ood	44
d	57
ood	66
d	78
d	94
d	115
d	120
ood	137
ood	147
d	160
ood	168
d	181
ood	190

match	position
od	11
d	18
od	24
od	45
d	57
od	67
d	78
d	94
d	115
d	120
od	138
od	148
d	160
od	169
d	181
od	191