How to retrieve a character in a string at a index in bash

Question

I am new to shell scripting I was wondering how do you index a string in bash For example in C++ we would do string[0] to get the first character in the string, how to do a similar thing in shell scripting?

mystring=helloworld

I want to traverse the string character by character For example in C++ I would do

for (auto i = 0;i < mystring.length(); i++)
      cout << mystring[i]

See [Change string char at index X](https://stackoverflow.com/q/9318021/4154375) for ways to change the character at an index in a string. — pjh, Mar 16 '22 at 20:17

score 1 · Answer 1 · answered Mar 16 '22 at 19:06

1

Use parameter expansion. ${#mystring} returns the string length, ${mystring:offset:length} returns a substring.

#! /bin/bash
mystring=helloworld
for ((i=0; i<${#mystring}; ++i)) ; do
    printf %s "${mystring:i:1}"
done

answered Mar 16 '22 at 19:06

choroba

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Can you please tell me If I want to change a character at a certain index on a string how can I do that? For example in C: mystring[0] = 't'; How to do that in bash? – Abdullah Chaudhry Mar 16 '22 at 19:23
2

Strings are immutable; you can't modify them in-place. – chepner Mar 16 '22 at 19:28
@AbdullahChaudhry that would be `i=1 str=abc str="${str:0:i}X${str:i+1}"; echo "$str"` – Fravadona Mar 16 '22 at 19:44

score 0 · Answer 2 · answered Mar 16 '22 at 19:25

0

echo "Hello" | awk '{split($0,a,""); print a[1]}'

print a[1] This is for Index Character a[2] ... a[n] you can do

{split($0,a,"") This is for character to split "" meaning split every character

answered Mar 16 '22 at 19:25

nude

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How to retrieve a character in a string at a index in bash

2 Answers2

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