CopyString
![CopyString 1:](Images/jpg/13435200907__Web.jpg)
This method copies the value of a key into a variable of the data type STRING, which can be of any length. The method returns the length of the copied string (including null termination). If the destination buffer is too small, it is emptied by a null termination and returned as length 0.
Syntax
METHOD CopyString : UDINT
VAR_INPUT
v : SJsonValue;
END_VAR
VAR_IN_OUT CONSTANT
pStr : STRING;
nStr : UDINT;
END_VAR
Return value
Name | Type |
---|---|
CopyString | UDINT |
Inputs
Name | Type |
---|---|
v | SJsonValue |
/
Inputs/Outputs
Name | Type |
---|---|
pStr | STRING |
nStr | UDINT |
Sample call:
The following JSON document is to be loaded into the DOM memory:
sMessage := ' {"serialNumber":"123","batteryVoltage":"1547mV","clickType":"SINGLE"}';
The value of the key "clickType" is to be extracted and stored in a variable of data type STRING. First, the JSON document is iteratively searched for the property "clickType".
jsonDoc := fbJson.ParseDocument(sMessage);
jsonIterator := fbJson.MemberBegin(jsonDoc);
jsonIteratorEnd := fbJson.MemberEnd(jsonDoc);
WHILE jsonIterator <> jsonIteratorEnd DO
sName := fbJson.GetMemberName(jsonIterator);
jsonValue := fbJson.GetMemberValue(jsonIterator);
IF sName = 'clickType' THEN
fbJson.CopyString(jsonValue, sString, SIZEOF(sString));
END_IF
jsonIterator := fbJson.NextMember(jsonIterator);
END_WHILE
After this run, the sString variable has the following content:
SINGLE