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##### 7.8.10.5 Information about Compositions

The functions in this section are actual functions; they compose their arguments according to the current language and other display modes, then return a certain measurement of the composition as an integer.

The `cwidth` function measures the width, in characters, of a composition. For example, ‘`cwidth(a + b)`’ is 5, and ‘`cwidth(a / b)`’ is 5 in Normal mode, 1 in Big mode, and 11 in TeX mode (for ‘`{a \over b}`’). The argument may involve the composition functions described in this section.

The `cheight` function measures the height of a composition. This is the total number of lines in the argument's printed form.

The functions `cascent` and `cdescent` measure the amount of the height that is above (and including) the baseline, or below the baseline, respectively. Thus ‘`cascent(x) + cdescent(x)`’ always equals ‘`cheight(x)`’. For a one-line formula like ‘`a + b`’, `cascent` returns 1 and `cdescent` returns 0. For ‘`a / b`’ in Big mode, `cascent` returns 2 and `cdescent` returns 1. The only formula for which `cascent` will return zero is ‘`cvspace(0)`’ or equivalents.