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A debugger that shows the programmer theline or expression in the source code that resulted in aparticular machine code instruction of a running programloaded in memory. This helps the programmer to analyse aprogram's behaviour in the high-level terms like source-levelflow control constructs, procedure calls, namedvariables, etc instead of machine instructions and memorylocations. Source-level debugging also makes it possible tostep through execution a line at a time and set source-levelbreakpoints.In order to support source-level debugging, the program mustbe compiled with this option enabled so that extra informationis included in the executable code to identify thecorresponding positions in the source code.A symbolic debugger is one level lower - it displays symbols(procedure and variable names) stored in the executable butnot individual source code lines.GDB is a widely used example of a source-level debugger.