Add mjson_snprintf() and mjson_aprintf()

README.md

@@ -38,10 +38,9 @@ if (mjson_get_bool(s, strlen(s), "$.b[1]", &boolval)) printf("%d\n", boolval);
 
 Print into a dynamically-allocated string:
 ```c
-char *result = NULL;      // It's important to initialise it to NULL
-mjson_printf(mjson_print_dynamic_buf, &result, "{%Q:%d}", "a", (int) 123);
-printf("%s\n", result);   // {"a":123}
-free(result);             // Caller must deallocate result
+char buf[100];
+mjson_snprintf(buf, sizeof(buf), "{%Q:%d}", "a", (int) 123);
+printf("%s\n", buf);   // {"a":123}
 ```
 
 Print into some custom target, for example, a network socket:
@@ -335,6 +334,23 @@ mjson_printf(&mjson_print_dynamic_buf, &s, "{%Q:%d, %Q:%M}", "a", 1, "b", m_prin
 free(s);
 ```
 
+## mjson_snprintf()
+
+```c
+int mjson_snprintf(char *buf, size_t len, const char *fmt, ...);
+```
+
+A convenience function that prints into a given string.
+
+## mjson_aprintf()
+
+```c
+char *mjson_aprintf(const char *fmt, ...);
+```
+
+A convenience function that prints into an allocated string. A returned
+pointer must be `free()`-ed by a caller.
+
 ## mjson_pretty()
 
 ```c

library.properties

@@ -1,5 +1,5 @@
 name=mjson
-version=1.2.2
+version=1.2.3
 author=Cesanta Software Limited <[email protected]>
 maintainer=Cesanta Software Limited <[email protected]>
 sentence=JSON parser, emitter, and JSON-RPC engine

mjson.c

@@ -495,6 +495,24 @@ int mjson_print_dynamic_buf(const char *ptr, int len, void *fndata) {
   }
 }
 
+int mjson_snprintf(char *buf, size_t len, const char *fmt, ...) {
+  va_list ap;
+  struct mjson_fixedbuf fb = {buf, (int) len, 0};
+  va_start(ap, fmt);
+  mjson_vprintf(mjson_print_fixed_buf, &fb, fmt, &ap);
+  va_end(ap);
+  return fb.len;
+}
+
+char *mjson_aprintf(const char *fmt, ...) {
+  va_list ap;
+  char *result = NULL;
+  va_start(ap, fmt);
+  mjson_vprintf(mjson_print_dynamic_buf, &result, fmt, &ap);
+  va_end(ap);
+  return result;
+}
+
 int mjson_print_null(const char *ptr, int len, void *userdata) {
   (void) ptr;
   (void) userdata;

mjson.h

@@ -123,6 +123,9 @@ int mjson_print_null(const char *ptr, int len, void *userdata);
 int mjson_print_fixed_buf(const char *ptr, int len, void *userdata);
 int mjson_print_dynamic_buf(const char *ptr, int len, void *userdata);
 
+int mjson_snprintf(char *buf, size_t len, const char *fmt, ...);
+char *mjson_aprintf(const char *fmt, ...);
+
 #if MJSON_ENABLE_PRETTY
 int mjson_pretty(const char *, int, const char *, mjson_print_fn_t, void *);
 #endif

test/unit_test.c

@@ -493,6 +493,16 @@ static void test_printf(void) {
     free(s);
   }
 
+  {
+    char buf[100], *s = mjson_aprintf("[%d]", 123);
+    int n = mjson_snprintf(buf, sizeof(buf), "{%g}", 1.23);
+    ASSERT(s != NULL);
+    ASSERT(n == 6);
+    ASSERT(strcmp(s, "[123]") == 0);
+    ASSERT(strcmp(buf, "{1.23}") == 0);
+    free(s);
+  }
+
   {
     char s[] = "0\n\xfeg";
     struct mjson_fixedbuf fb = {tmp, sizeof(tmp), 0};