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==Description==
===Basic structure and statements===
Like many ALGOL systems, and the later [[Pascal (programming language)|Pascal]], the basic structure of SAIL is based on the ''block'', which is denoted by the code between the keywords {{code|BEGIN}} and {{code|END}}. Within a block there is further structure, with the ''declarations'' of local variables at the top, if any, and the code, or ''statements'', following. In contrast to most dialects, SAIL allowed one to place a string after the {{code|BEGIN}}, like {{code|BEGIN "program"}}, and then end the block with {{code|END "program"}}. The compiler would use these, if entered, to check for proper bracketing.{{sfn|Smith|1976|p=13}} SAIL did not include the equivalent of a {{code|PROGRAM}} block as in Pascal, nor a {{code|main}} as in C, execution stared with the first line of code in the outermost block.{{sfn|Smith|1976|p=48}}
Standard statements included {{code|IF...THEN...ELSE}},{{sfn|Smith|1976|p=11}} {{code|FOR...STEP...UNTIL...DO}},{{sfn|Smith|1976|p=15}} {{code|WHILE...DO}} for top-tested loops, {{code|WHILE...UNTIL}} for bottom-tested, and {{code|GOTO}} which used a label.{{sfn|Smith|1976|p=17}} The {{code|CASE}} was similar to {{code|switch}} in C, but normally used a somewhat different syntax, like {{code|CASE i OF ("Zero","One","Two");}}, which returns the appropriate string based on the value of i.{{sfn|Smith|1976|p=11}} If one wanted to test explicit values in the CASE, the values had to be in square brackets:
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