basic语言的基本命令

basic语言的基本命令Basic command (2009-09-2420:34:02)Reprint TAB: it classification: compiler authoringThe assign statement (LET) (format) LET variable = the expression (function) assigns a data to a variable. The essay is made out of the basic statement. The value of the expression is the data to be assigned to the variable. The expression can be either a number or an arithmetic. 【 application 】 LET A = 5 (2) suspension of statements (PAUSE) PAUSE time format 】【【 features 】 to suspend execution, or delay for A period of time. 【 description 】 (1) when let robot motion, is to control the robot by the length of time the distance of the forward and backward, and the left and right rotation Angle. The specific value of time is the length of time, which can be accurate to milliseconds. The phrase "PAUSE 1000" means that the delay time is set to 1 second. 3. The END of the statement (END) END format 】【【 features 】 terminates 4. Loop statement (FOR/NEXT) FOR loop variable = initial value TO the final STEP STEP length (...... The circulatory body... )NEXT variable FOR loop statements (circular entrance) NEXT cycle final value statements (cycle export) 【 features 】 do statement used to perform a fixed number of repetitions. The initial value, final value, and step length of the loop variable can be constant or variable. When the STEP length is 1, STEPcan be omitted. It is necessary to use the name of the loop variable. The nested layer of the loop is no more than 8 layers.The SOUND (SOUND) [function] gives the SOUND of a given tone for the duration of the specified duration. The module has been integrated into port 10 of the general robot motherboard. Voice frequency value, is the actual frequency value, can send out the frequency of the people's ears to hear, in the practical application, can be appropriately changing the frequency of the sound to correct intonation, sound frequency zero for the rest. Unconditional transfer statement (GOTO) (format) the GOTO mark (function) unconditionally moves to the specified row label to execute the program. An article is a symbol for an address. The bidding number is terminated by the colon and appears before the execution statement, not before the non-executable. 7．注释语句（REM）【格式】 REM 字符串【功能】释语句的主要作用是为了增强程序的可读性，在程序执行中并不被执行，即REM”后的语句只是起到说明作用。

【说明】⑴ 为了提高程序的可读性，可以在程序的适当位置加上一些注释，注释可以放在程序的任何位置。

⑵ REM后面可以是任何内容。

⑶ REM可以用单引号代替“’”。

【应用】 REM 机器人走图形 8．条件转移语句（IF/THEN）【格式】IF 条件表达式 THEN 标号【功能】根据条件表达式是否成立，决定程序的流向。

【说明】⑴ 在条件语句中，条件表达式的值如果为真，那么转到给定的标号去执行程序，否则执行条件语句的下一个语句。

⑵ 在使用条件语句前，要对算术表达式、关系表达式、逻辑表达式以及有关知识有一个初步的了解和认识。

① 算术表达式：算术运算符：+(加)、-(减)、*(乘)、/(除)、^(乘方)、（、）圆括号算术表达式：用算术运算符和括号，将常量、变量和函数连接起来的式子。

② 关系表达式关系运算符：=（等于）、<>（不等于）、=>或>=（大于等于）、=<或<=（小于等于）、>、（大于）< （小于）。

关系表达式的运算结果是一个逻辑值，逻辑值只有两个，真（1）和假（0）。

The condition is true, its value is true, the condition is not valid, its value is false. Logical expression logic operator: AND (with), OR (OR), NOT (NOT). Logical expression: a formula that connects multiple relational expressions using logical operators. The result of the logical expression is a logical value. The results are as follows: A AND B are true, B is true, AND the logical expression is true. A OR B, A, and B, as long as one is true, the logical expression is true. In the combination of logical operation, relational operation and mathematical operation, the order of operation must be indicated in parentheses. The range of mathematical operations is 0 ~ 65535, no more than the integer division, which is the quotient. Reading statement/set statement (READ/DATA) (format) READ variable 1, variable 2,... Variable N DATA constant 1, constant 2,... Constant N, which USES DATA in the DATA statement to assign values to the corresponding variable in the READ statement. 【 description 】 the variable 1, variable 1,... The variable N is a comma-separated set of variables, with no sign at the end. Constant 1, constant 2,... Constant N is a comma-separated set of data, with no sign at the end. The READ/DATA statement must be paired, and the READ statement can only be a variable, not a constant or an expression. (4) the DATA in the DATA statement can only be constant, not a variable or expression, and the DATA statement non-executive statements, the location of the DATA statement without restrictions, but must be before the END statement. The READ statement is READ in order, and if the reading exceeds the actual data, the data READ is unknowable. RESTORE the data area statement (RESTORE) [format] RESTORE the RESTORE statement, resetting the reading pointer to the start location. The RESTORE statement is usedin conjunction with the reading statement/set statement (READ/DATA).When the program executes the RESTORE statement and then executes the READ statement, the variable in the READ statement begins to READ the DATA from the first DATA in the first DATA statement in the program. Multiple BRANCH statements (BRANCH)The BRANCH variable, (the label 0, the label 1, the label n), turns to different Numbers depending on the value of the variable. If the value of the variable is zero, then go to the label 0; Go to the label 1, and so on. If the value of the variable is greater than n, then execute the next statement. While this statement is used to those who need according to the value of a variable for different occasions, to deal with so that you can use multiple branching statements go to a few different label. 12. The conditions for statement 1 (the DO WHILE LOOP) [form] DO WHILE conditional expression block 1 block 2 LOOP EXIT DO statement execution function 】【 DO WHILE statement when they check whether a conditional expression. The conditional expression is set up, and the LOOP body language is executed, and the DO WHILE statement is returned automatically when the LOOP statement is executed, otherwise the statement under the LOOP statement is executed. Each cycle begins with an examination of whether the conditional expression is established, and if it is not established at the beginning, the loop terminates immediately. In the loop statement, you must change the statement of the variable in the conditional expression, otherwise you will have a dead loop, and you can EXIT the loop with the EXIT DO statement. The "EXIT DO" is optional, and the "do-loop" LOOP contains multiple EXITDO statements. The "do-loop" LOOP statement can be embedded in the block IF statement as a whole, and the block IF statement can be embedded in the do-loop statement as a whole. The "do-loop" LOOP statement can be nested, or it may be nested with the for-next LOOP. 13. Conditions for statement 2 (DO - LOOP WHILE) block format 】【 1 block 2 LOOP EXIT DO statement WHILE conditional expression 【 features 】 to execute a LOOP body unconditionally when performing a DO statement. When performing the LOOP statement, check if the conditional expression is formed.The conditional expression automatically returns the DO statement, otherwise the statement under the LOOP statement is executed. Verify that the expression is established at the end of each loop, rather than at the beginning of the loop. The main difference between it and the DO WHILE loop is that the first cycle must be executed. A cycle must be performed. 14. Statements define a variable (SYMBOL) SYMBOL variables = type format 】【【 features 】 byte variables, it is a variable, words are required to use the SYMBOL to use statements define. In the general QBASIC language, bit0 ~ bit32, byte variable b0 ~ b4, word variable w0 ~ w1, can be used directly. In addition to the above variables, the other byte variables can be used directly; Other variables, word variables, must be defined using the SYMBOL statement. (3) = WORD SYMBOL variables defined as double BYTE variables SYMBOL = BYTE is defined as a single-byte variables can be omitted (not write) = BIT is defined as a variable SYMBOL variables (4) in a program, most of the available variables is 128 bytes, such as using the double BYTE variable, make two Spaces. Conditional branch statements 15. Block structures (IF/THEN/ELSE) IF conditionalexpression format 】【 THEN block 1 ELSE block 2 END IF 【 features 】 IF conditional expression, execute the statement block 1, THEN turn to the next statement in the END IF statements. When the conditional expression is not valid, the ELSE and block 2 are executed, then the next statement of the END IF statement is executed. The phrase "IF to END IF" is a conditional conditional transfer statement. Diction in the block structure conditional branch statements, but lack the ELSE and block 2, when the conditional expression, does not perform any statements, go to the END of the IF statement to the next statement execution. The word "END IF" is two words, and there must be Spaces in the middle.。