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StringJoin

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description

StringJoin["s1", "s2", ...]

Concatenates strings together. StringJoin[{"s1", "s2", ...}] flattens all lists. The infix form is "s1" \<> "s2" \<> ...

Examples (6)

Every input below was run against the current Mathilda build and its output recorded.

Basic examples (6)

In[1]:= StringJoin["abcd", "ABCD", "xyz"]
Out[1]= "abcdABCDxyz"

In[2]:= "abcd" <> "ABCD" <> "xyz"
Out[2]= "abcdABCDxyz"

In[3]:= StringJoin[{{"AB", "CD"}, "XY"}]
Out[3]= "ABCDXY"

In[4]:= StringJoin[]
Out[4]= ""

In[5]:= StringJoin["a", x]
Out[5]= StringJoin["a", x]

In[6]:= StringJoin[Characters["hello"]]
Out[6]= "hello"

Implementation notes

builtin_stringjoin gathers all leaf strings into a growable const char** array via the recursive helper collect_strings, which descends through any List wrappers and borrows (does not copy) each EXPR_STRING's data.string; any non-string, non-List leaf aborts with NULL (unevaluated). It then sums the lengths, mallocs one buffer of total_len + 1, memcpys each fragment in order, and returns a single EXPR_STRING. The zero-argument form yields "". Registered with ATTR_FLAT | ATTR_ONEIDENTITY | ATTR_PROTECTED, so the evaluator flattens nested StringJoin (and the <> infix operator) before the builtin runs.

Attributes: Flat, OneIdentity, Protected.

References

See also: Flat, OneIdentity