set some_string "Name/is/ComplexSTRUCTUre" 

convert this string to,

some_string = "Name/is/ComplexSTR.CTUre" 

i.e replacing first "U" to "."

3 Answers

Try This,

set replaced_string [regsub "U" $some_string "."] puts $replaced_string 

Another Option,

set pos [string first "U" $some_string] set replaced_string [string replace $some_string $pos $pos "."] puts $replaced_string 

Here your "Name/is" portion should not contain any "U"

More information can be found here tcl string replacement

Use of regsub is overkill for plain strings. If you simply wish to replace one set of substrings with another, string map is your friend:

set s "Name/is/ComplexSTRUCTUre" set s [string map {U .} $s] 

This, however, will replace all Us with dots -- as your question's title suggests.

If, however, you want only the first U replaced -- as the text of your question implies, then AxT_8041's second option is the most suitable.

you can use:

string replace <num1> <num2> <To_be_replaced> 

example:

set a [get_attr [get_cells -filter <cell_name> ] ref_name] <cell_name> string replace 5 8 NAME <cell_NAME> 

ncG1vNJzZmirpJawrLvVnqmfpJ%2Bse6S7zGiorp2jqbawutJoam9xaGiGeH%2BOoaawZaSkerOxz6WYnJ1dpa6zwMicrKWZomKwqa3RmpqtnaJitq950q2poqaXYsSqwMdmq5ykXaiws7XPrQ%3D%3D