chore(str): change fmt_str to s_fmt

clib.json

@@ -1,6 +1,6 @@
 {
   "name": "libutil",
-  "version": "0.0.13",
+  "version": "0.1.13",
   "author": "Matthew Zito",
   "repo": "exbotanical/libutil",
   "license": "MIT",

include/libutil.h

@@ -229,7 +229,7 @@ void buffer_free(buffer_t *buf);
 /**
  * Returns a formatted string. Uses printf syntax.
  */
-char *fmt_str(char *fmt, ...);
+char *s_fmt(char *fmt, ...);
 
 /**
  * s_truncate truncates the given string `s` by `n` characters.

src/str.c

@@ -1,4 +1,5 @@
 #include <ctype.h>  // for toupper
+#include <stdarg.h>
 #include <stdio.h>  // for snprintf
 #include <stdlib.h>
 #include <string.h>
@@ -212,3 +213,23 @@ array_t *s_split(const char *s, const char *delim) {
 
   return tokens;
 }
+
+char *s_fmt(char *fmt, ...) {
+  va_list args, args_cp;
+  va_start(args, fmt);
+  va_copy(args_cp, args);
+
+  // Pass length of zero first to determine number of bytes needed
+  unsigned int n = vsnprintf(NULL, 0, fmt, args) + 1;
+  char *buf = malloc(n);
+  if (!buf) {
+    return NULL;
+  }
+
+  vsnprintf(buf, n, fmt, args_cp);
+
+  va_end(args);
+  va_end(args_cp);
+
+  return buf;
+}

t/main.c

@@ -6,7 +6,6 @@ int main() {
 
   run_array_tests();
   run_buffer_tests();
-  run_fmt_tests();
   run_str_tests();
 
   done_testing();

t/str_test.c

@@ -290,6 +290,13 @@ void test_s_split_end_match(void) {
   array_free_ptrs(paths);
 }
 
+void test_s_fmt(void) {
+  char *formatted = s_fmt("%s %d %s", "test", 11, "string");
+  is(formatted, "test 11 string", "formats each part into a single string");
+
+  free(formatted);
+}
+
 void run_str_tests(void) {
   test_s_copy();
 
@@ -325,4 +332,6 @@ void run_str_tests(void) {
   test_s_split_no_match();
   test_s_split_empty_input();
   test_s_split_end_match();
+
+  test_s_fmt();
 }

t/tests.h

@@ -3,7 +3,6 @@
 
 void run_array_tests(void);
 void run_buffer_tests(void);
-void run_fmt_tests(void);
 void run_str_tests(void);
 
 #endif /* TESTS_H */