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How do I use an if statement to check if a certain string of text is in another set of characters?

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0

I want to make an if statement that will return a value when a certain characters are in another set of texts. For example if I have the words water, and fire. I want to make an if statement that will check if the word I give it has characters "wa" then it will return a value of 1. Something along the lines of this.

set word "water"
set tempvar 0
if $word has characters "wa" 
 set tempvar 1

tcl

share|improve this question

edited Mar 26 at 19:42

Donal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

asked Mar 26 at 19:31

MakuzaMakuza

1

add a comment | 

0

I want to make an if statement that will return a value when a certain characters are in another set of texts. For example if I have the words water, and fire. I want to make an if statement that will check if the word I give it has characters "wa" then it will return a value of 1. Something along the lines of this.

set word "water"
set tempvar 0
if $word has characters "wa" 
 set tempvar 1

tcl

share|improve this question

edited Mar 26 at 19:42

Donal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

asked Mar 26 at 19:31

MakuzaMakuza

1

add a comment | 

I want to make an if statement that will return a value when a certain characters are in another set of texts. For example if I have the words water, and fire. I want to make an if statement that will check if the word I give it has characters "wa" then it will return a value of 1. Something along the lines of this.

set word "water"
set tempvar 0
if $word has characters "wa" 
 set tempvar 1

tcl

share|improve this question

edited Mar 26 at 19:42

Donal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

asked Mar 26 at 19:31

MakuzaMakuza

1

set word "water"
set tempvar 0
if $word has characters "wa" 
 set tempvar 1

share|improve this question

edited Mar 26 at 19:42

Donal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

asked Mar 26 at 19:31

MakuzaMakuza

1

share|improve this question

edited Mar 26 at 19:42

Donal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

asked Mar 26 at 19:31

MakuzaMakuza

1

edited Mar 26 at 19:42

Donal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

edited Mar 26 at 19:42

Donal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

asked Mar 26 at 19:31

MakuzaMakuza

1

asked Mar 26 at 19:31

MakuzaMakuza

1

3 Answers
3

active

oldest

votes

2

The simplest (and fastest!) way to search for whether a substring is present is the string first command; that returns -1 if the substring isn't there, and the (first) index of where it is found when the substring is present.

if [string first "wa" $word] >= 0 
 set tempvar 1

The other technique that works well is one of the lesser known operating modes of Tcl's regular expression engine: if the RE starts with ***= then the rest of the string is a literal.

# This is marginally slower than string first; the overhead of the RE engine matters a little
if [regexp ***=wa $word] 
 set tempvar 1

Note that if you were asking if it was a prefix, other commands are more suitable (string equal with the -length option, or string match). And use lsearch if you want to know if a particular value is an element in a list, instead of string searching.

share|improve this answer

answered Mar 26 at 19:49

Donal FellowsDonal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The reason you have to be a little careful is that a lot of the more sophisticated matchers have important metacharacters. It doesn't matter when looking for wa, but if you're looking for wa or *wa* it can matter a lot. A little care at the beginning makes life much easier later on.
  
  – Donal Fellows
  Mar 29 at 9:38
  

  
  
  
  

add a comment | 

1

I would encapsulate this in a proc:

proc string_contains haystack needle 
 expr [string first $needle $haystack] != -1

then

% string_contains water wa
1
% string_contains fire wa
0

and

% if [string_contains water wa] then puts yes else puts no
yes
% if [string_contains fire wa] then puts yes else puts no
no

share|improve this answer

answered Mar 26 at 22:02

glenn jackmanglenn jackman

177k2626 gold badges155155 silver badges251251 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  One has to be careful about the empty string as needle then, string first is just broken in this respect: string_contains water "" will give 0.
  
  – mrcalvin
  Mar 28 at 23:36
  

  
  
  
  

add a comment | 

0

Generally, in any language, for matching purpose, Regular Expressions are used, here used as regexp $pattern $string and return 1 if there is a match.

set word "water" 
set tempvar 0 
if [regexp "wa" $word] 
 set tempvar 1 
 
puts $tempvar

share|improve this answer

answered Mar 31 at 4:56

DrektzDrektz

3488 bronze badges

add a comment | 

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2

The simplest (and fastest!) way to search for whether a substring is present is the string first command; that returns -1 if the substring isn't there, and the (first) index of where it is found when the substring is present.

if [string first "wa" $word] >= 0 
 set tempvar 1

The other technique that works well is one of the lesser known operating modes of Tcl's regular expression engine: if the RE starts with ***= then the rest of the string is a literal.

# This is marginally slower than string first; the overhead of the RE engine matters a little
if [regexp ***=wa $word] 
 set tempvar 1

Note that if you were asking if it was a prefix, other commands are more suitable (string equal with the -length option, or string match). And use lsearch if you want to know if a particular value is an element in a list, instead of string searching.

share|improve this answer

answered Mar 26 at 19:49

Donal FellowsDonal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The reason you have to be a little careful is that a lot of the more sophisticated matchers have important metacharacters. It doesn't matter when looking for wa, but if you're looking for wa or *wa* it can matter a lot. A little care at the beginning makes life much easier later on.
  
  – Donal Fellows
  Mar 29 at 9:38
  

  
  
  
  

add a comment | 

2

The simplest (and fastest!) way to search for whether a substring is present is the string first command; that returns -1 if the substring isn't there, and the (first) index of where it is found when the substring is present.

if [string first "wa" $word] >= 0 
 set tempvar 1

The other technique that works well is one of the lesser known operating modes of Tcl's regular expression engine: if the RE starts with ***= then the rest of the string is a literal.

# This is marginally slower than string first; the overhead of the RE engine matters a little
if [regexp ***=wa $word] 
 set tempvar 1

Note that if you were asking if it was a prefix, other commands are more suitable (string equal with the -length option, or string match). And use lsearch if you want to know if a particular value is an element in a list, instead of string searching.

share|improve this answer

answered Mar 26 at 19:49

Donal FellowsDonal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The reason you have to be a little careful is that a lot of the more sophisticated matchers have important metacharacters. It doesn't matter when looking for wa, but if you're looking for wa or *wa* it can matter a lot. A little care at the beginning makes life much easier later on.
  
  – Donal Fellows
  Mar 29 at 9:38
  

  
  
  
  

add a comment | 

The simplest (and fastest!) way to search for whether a substring is present is the string first command; that returns -1 if the substring isn't there, and the (first) index of where it is found when the substring is present.

if [string first "wa" $word] >= 0 
 set tempvar 1

The other technique that works well is one of the lesser known operating modes of Tcl's regular expression engine: if the RE starts with ***= then the rest of the string is a literal.

# This is marginally slower than string first; the overhead of the RE engine matters a little
if [regexp ***=wa $word] 
 set tempvar 1

Note that if you were asking if it was a prefix, other commands are more suitable (string equal with the -length option, or string match). And use lsearch if you want to know if a particular value is an element in a list, instead of string searching.

share|improve this answer

answered Mar 26 at 19:49

Donal FellowsDonal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

if [string first "wa" $word] >= 0 
 set tempvar 1

# This is marginally slower than string first; the overhead of the RE engine matters a little
if [regexp ***=wa $word] 
 set tempvar 1

share|improve this answer

answered Mar 26 at 19:49

Donal FellowsDonal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

answered Mar 26 at 19:49

Donal FellowsDonal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

answered Mar 26 at 19:49

Donal FellowsDonal Fellows

106k1515 gold badges118118 silver badges182182 bronze badges

1

I would encapsulate this in a proc:

proc string_contains haystack needle 
 expr [string first $needle $haystack] != -1

then

% string_contains water wa
1
% string_contains fire wa
0

and

% if [string_contains water wa] then puts yes else puts no
yes
% if [string_contains fire wa] then puts yes else puts no
no

share|improve this answer

answered Mar 26 at 22:02

glenn jackmanglenn jackman

177k2626 gold badges155155 silver badges251251 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  One has to be careful about the empty string as needle then, string first is just broken in this respect: string_contains water "" will give 0.
  
  – mrcalvin
  Mar 28 at 23:36
  

  
  
  
  

add a comment | 

1

I would encapsulate this in a proc:

proc string_contains haystack needle 
 expr [string first $needle $haystack] != -1

then

% string_contains water wa
1
% string_contains fire wa
0

and

% if [string_contains water wa] then puts yes else puts no
yes
% if [string_contains fire wa] then puts yes else puts no
no

share|improve this answer

answered Mar 26 at 22:02

glenn jackmanglenn jackman

177k2626 gold badges155155 silver badges251251 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  One has to be careful about the empty string as needle then, string first is just broken in this respect: string_contains water "" will give 0.
  
  – mrcalvin
  Mar 28 at 23:36
  

  
  
  
  

add a comment | 

I would encapsulate this in a proc:

proc string_contains haystack needle 
 expr [string first $needle $haystack] != -1

then

% string_contains water wa
1
% string_contains fire wa
0

and

% if [string_contains water wa] then puts yes else puts no
yes
% if [string_contains fire wa] then puts yes else puts no
no

share|improve this answer

answered Mar 26 at 22:02

glenn jackmanglenn jackman

177k2626 gold badges155155 silver badges251251 bronze badges

proc string_contains haystack needle 
 expr [string first $needle $haystack] != -1

% string_contains water wa
1
% string_contains fire wa
0

% if [string_contains water wa] then puts yes else puts no
yes
% if [string_contains fire wa] then puts yes else puts no
no

share|improve this answer

answered Mar 26 at 22:02

glenn jackmanglenn jackman

177k2626 gold badges155155 silver badges251251 bronze badges

answered Mar 26 at 22:02

glenn jackmanglenn jackman

177k2626 gold badges155155 silver badges251251 bronze badges

answered Mar 26 at 22:02

glenn jackmanglenn jackman

177k2626 gold badges155155 silver badges251251 bronze badges

0

Generally, in any language, for matching purpose, Regular Expressions are used, here used as regexp $pattern $string and return 1 if there is a match.

set word "water" 
set tempvar 0 
if [regexp "wa" $word] 
 set tempvar 1 
 
puts $tempvar

share|improve this answer

answered Mar 31 at 4:56

DrektzDrektz

3488 bronze badges

add a comment | 

0

Generally, in any language, for matching purpose, Regular Expressions are used, here used as regexp $pattern $string and return 1 if there is a match.

set word "water" 
set tempvar 0 
if [regexp "wa" $word] 
 set tempvar 1 
 
puts $tempvar

share|improve this answer

answered Mar 31 at 4:56

DrektzDrektz

3488 bronze badges

add a comment | 

Generally, in any language, for matching purpose, Regular Expressions are used, here used as regexp $pattern $string and return 1 if there is a match.

set word "water" 
set tempvar 0 
if [regexp "wa" $word] 
 set tempvar 1 
 
puts $tempvar

share|improve this answer

answered Mar 31 at 4:56

DrektzDrektz

3488 bronze badges

set word "water" 
set tempvar 0 
if [regexp "wa" $word] 
 set tempvar 1 
 
puts $tempvar

share|improve this answer

answered Mar 31 at 4:56

DrektzDrektz

3488 bronze badges

answered Mar 31 at 4:56

DrektzDrektz

3488 bronze badges

answered Mar 31 at 4:56

DrektzDrektz

3488 bronze badges