hello friend i am useing sscanf function in my program. the valid packet recived from the serial port using the intrupt . here i am getting the string in RxBuf using intr and main() { sscanf(&RxBuf[0],"%lf,%c,%lf,%c,%lf,%c,%lf,%lf,%lf",&time,&valid,&latnow,&latnowdir,&lonnow,&lonnowdir,&speed,&course,&date); if(valid=='A') { here i write my application code; } } in this above code if valid packet recived from serial port the valid loop does not exeed. plz slove this prob