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(C++) Check if Integer Exists at JSON PathDemonstrates how to get an integer value at a JSON path, and how to check to see if it exists.
#include <CkJsonObject.h> void ChilkatSample(void) { CkJsonObject json; bool success; // First build simple JSON.. json.UpdateInt("test.abc",100); json.put_EmitCompact(false); std::cout << json.emit() << "\r\n"; // This is our JSON: // { // "test": { // "abc": 100, // } // } const char *path = "test.notHere"; // The call to IntOf will return 0, because it's not present. // But how do we know if it really was present, and the value was truly 0? int val = json.IntOf(path); std::cout << "val = " << val << "\r\n"; // We cannot use LastMethodSuccess because LastMethodSuccess only applies // to methods that: // - return a string // - return a new Chilkat object, binary bytes, or a date/time. // - returns a boolean status where true = success and false = failed. // - returns an integer where failure is defined by a return value less than zero. // The IntOf method fits none of these requirements, and therefore the LastMethodSuccess // is not a valid indicator.. bool wasFound = json.get_LastMethodSuccess(); std::cout << "wasFound = " << wasFound << " (not a valid indicator)" << "\r\n"; // Instead, if the returned value is 0, we can double-check to see if the member was truly there.. if (val == 0) { wasFound = json.HasMember(path); std::cout << "wasFound = " << wasFound << "\r\n"; if (wasFound == true) { std::cout << "The value was present and is 0." << "\r\n"; } else { std::cout << "no member is present at test.notHere" << "\r\n"; } } else { std::cout << "val = " << val << "\r\n"; } // Alternatively, you could check to see if the member exists beforehand.. if (json.HasMember(path) == true) { std::cout << "val = " << json.IntOf(path) << "\r\n"; } else { std::cout << "no member at " << path << "\r\n"; } } |
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