JSON_Iterate

Output the next key-value pair or value from a collection.

JSONStatus_t JSON_Iterate( const char * buf,
                           size_t max,
                           size_t * start,
                           size_t * next,
                           JSONPair_t * outPair );

This function may be used in a loop to output each key-value pair from an object, or each value from an array. For the first invocation, the integers pointed to by start and next should be initialized to 0. These will be updated by the function. If another key-value pair or value is present, the output structure is populated and JSONSuccess is returned; otherwise the structure is unchanged and JSONNotFound is returned.

Parameters

[in]	buf	The buffer to search.
[in]	max	size of the buffer.
[in,out]	start	The index at which the collection begins.
[in,out]	next	The index at which to seek the next value.
[out]	outPair	A pointer to receive the next key-value pair.

Note

This function expects a valid JSON document; run JSON_Validate() first.

For an object, the outPair structure will reference a key and its value. For an array, only the value will be referenced (i.e., outPair.key will be NULL).

Returns

JSONSuccess if a value is output; JSONIllegalDocument if the buffer does not contain a collection; JSONNotFound if there are no further values in the collection.

Example

// Variables used in this example.
static char * json_types[] =
{
    "invalid",
    "string",
    "number",
    "true",
    "false",
    "null",
    "object",
    "array"
};
 
void show( const char * json,
           size_t length )
{
    size_t start = 0, next = 0;
    JSONPair_t pair = { 0 };
    JSONStatus_t result;
 
    result = JSON_Validate( json, length );
    if( result == JSONSuccess )
    {
        result = JSON_Iterate( json, length, &start, &next, &pair );
    }
 
    while( result == JSONSuccess )
    {
        if( pair.key != NULL )
        {
            printf( "key: %.*s\t", ( int ) pair.keyLength, pair.key );
        }
 
        printf( "value: (%s) %.*s\n", json_types[ pair.jsonType ],
                ( int ) pair.valueLength, pair.value );
 
        result = JSON_Iterate( json, length, &start, &next, &pair );
    }
}

See core_json.h for docs.