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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 <C_CkJsonObjectW.h> void ChilkatSample(void) { HCkJsonObjectW json; BOOL success; const wchar_t *path; int val; BOOL wasFound; json = CkJsonObjectW_Create(); // First build simple JSON.. CkJsonObjectW_UpdateInt(json,L"test.abc",100); CkJsonObjectW_putEmitCompact(json,FALSE); wprintf(L"%s\n",CkJsonObjectW_emit(json)); // This is our JSON: // { // "test": { // "abc": 100, // } // } 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? val = CkJsonObjectW_IntOf(json,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.. wasFound = CkJsonObjectW_getLastMethodSuccess(json); 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 = CkJsonObjectW_HasMember(json,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 (CkJsonObjectW_HasMember(json,path) == TRUE) { wprintf(L"val = %d\n",CkJsonObjectW_IntOf(json,path)); } else { wprintf(L"no member at %s\n",path); } CkJsonObjectW_Dispose(json); } |
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