SIM900A Arduino Uno

Sir,please tell me how to store the reply of AT+CCLK in a string?
I have tried read.String but it’s not working. I want to store the current time in a string and then wants to compare it with the SMS received to perform a specific task at a specific time.
I don’t want to use DS3231 RTC.

How are you trying to read the string of AT+CCLK? command?