concat manual page - Tcl Built-In Commands

## Tcl8.6.4 Documentation > Tcl Commands, version 8.6.4 > concat

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### NAME

concat — Join lists together

### SYNOPSIS

concat ?arg arg ...?

### DESCRIPTION

This command joins each of its arguments together with spaces after trimming leading and trailing white-space from each of them. If all of the arguments are lists, this has the same effect as concatenating them into a single list. It permits any number of arguments; if no args are supplied, the result is an empty string.

### EXAMPLES

Although concat will concatenate lists, flattening them in the process (so giving the following interactive session):

    % concat a b {c d e} {f {g h}}
    a b c d e f {g h}

it will also concatenate things that are not lists, as can be seen from this session:

    % concat " a b {c   " d "  e} f"
    a b {c d e} f

Note also that the concatenation does not remove spaces from the middle of values, as can be seen here:

    % concat "a   b   c" { d e f }
    a   b   c d e f

(i.e., there are three spaces between each of the a, the b and the c).

### SEE ALSO

append, eval, join

### KEYWORDS

concatenate, join, list
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