```{index} single: cstring; B function ``` ```{index} single: B::cstring; Perl function ``` # cstring Return `$sv`'s contents as a double-quoted C-style string literal. ## Synopsis ```perl B::cstring("hi\tthere"); # "hi\tthere" B::cstring(undef); # 0 ``` Unprintable bytes become `\n`, `\t`, `\r`, `\a`, `\b`, `\f`, `\v`, or octal escapes. An undef SV renders as the literal `0` (no quotes), which is the convention `B::Deparse` depends on. Used by back-ends that emit C-level source.