THE DIFFERENCES BETWEEN STRUCTURED LANGUAGE AND UNSTRUCTURED LANGUAGE: PROGRAMING LANGUAGE

INTRODUCTION
A program in a non-structured language usually consists of sequentially ordered commands, or statements, usually one in each line. The lines are usually numbered or may have labels: this allows the flow of execution to jump to any line in the program. Non-structured programming introduces basic control flow concepts such as loops, branches and jumps. Although there is no concept of procedures in the non-structured paradigm[citation needed], subroutines are allowed. Unlike a procedure, a subroutine may have several entry and exit points, and a direct jump into or out of subroutine is (theoretically) allowed. This flexibility allows realization of coroutines. There is no concept of locally scoped variables in non-structured programming (although for assembly programs, general purpose registers may serve the same purpose after saving on entry), but labels and variables can have a limited area of effect (for example, a group of lines). This means there is no (automatic) context refresh when calling a subroutine, so all variables might retain their values from the previous call. This makes general recursion difficult, but some cases of recursion--where no subroutine state values are needed after the recursive call--are possible if variables dedicated to the recursive subroutine are explicitly cleared (or re-initialized to their original value) on entry to the subroutine. The depth of nesting also may be limited to one or two levels. Non-structured languages allow only basic data types, such as numbers, strings and arrays[citation needed] (numbered sets of variables of the same type). The introduction of arrays into non-structured languages was a notable step forward, making stream data processing possible despite the lack of structured data types  The main difference between structured and unstructured programming language is that a structured programming language allows a programmer to code a program by diving the whole program into smaller units or modules. In unstructured programming language, the program must be written as a single continuous, i.e. nonstop or unbroken block.