[WJG] 2013-03-16:  Needed a simple way of counting the occurrences of one
string in another. I was surprised to find that the standard Tcl string command
had no offering.


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proc string_occurrences {needleString haystackString} {

    set j [string first $needleString $haystackString 0]
    if {$j == -1} {return 0}

    set i 0
    while {$j != -1 } {
        set j [string first $needleString $haystackString [incr j]]
        incr i
    }

    return $i
}
======

[SEH] How about:

 llength [regexp -all -inline (?=$needleString) $haystackString]

[AMG]: This gets into trouble when $needleString contains regular expression metacharacters, all of which will need to be preceded by backslashes.  Try this:

======
regsub -all {[][{}()\\^$*+?.]} $needleString {\\&} needleString
======

[PYK]:  Another option is [ycl]::string::delimit:

======
package require ycl::string
namespace import [yclprefix]::string::delimit

set data "one and two and three and four andand five"
delimit $data string and format count
# 5
======

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