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(Unicode 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 <CkJsonObjectW.h> void ChilkatSample(void) { CkJsonObjectW json; bool success; // First build simple JSON.. json.UpdateInt(L"test.abc",100); json.put_EmitCompact(false); wprintf(L"%s\n",json.emit()); // This is our JSON: // { // "test": { // "abc": 100, // } // } const wchar_t *path = L"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); wprintf(L"val = %d\n",val); // 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(); wprintf(L"wasFound = %d (not a valid indicator)\n",wasFound); // 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); wprintf(L"wasFound = %d\n",wasFound); if (wasFound == true) { wprintf(L"The value was present and is 0.\n"); } else { wprintf(L"no member is present at test.notHere\n"); } } else { wprintf(L"val = %d\n",val); } // Alternatively, you could check to see if the member exists beforehand.. if (json.HasMember(path) == true) { wprintf(L"val = %d\n",json.IntOf(path)); } else { wprintf(L"no member at %s\n",path); } } |
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