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en:iot-open:programming_fundamentals_rtu:program_control_structures [2018/01/18 13:37] – Agrisnik | en:iot-open:programming_fundamentals_rtu:program_control_structures [2020/07/20 09:00] (current) – external edit 127.0.0.1 | ||
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</ | </ | ||
+ | The example when the //x// variable is compared and in the cases when it is higher than //10//, the // | ||
<code c> | <code c> | ||
if (x> | if (x> | ||
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==== Comparison operators ==== | ==== Comparison operators ==== | ||
- | There are multiple comparison operators used for comparing variables and values. Comparison operators are following: | + | There are multiple comparison operators used for comparing variables and values. All of these operators compare the value of the variable on the left to the value of the variable on the right. Comparison operators are following: |
- | * == (equal to) - | + | * == (equal to) - if they are equal, the result is //TRUE//, otherwise //FALSE//. |
- | * != (not equal to) - | + | * != (not equal to) - if they are not equal, the result is //TRUE//, otherwise //FALSE//. |
- | * < (less than) - | + | * < (less than) - if the value of the variable on the left is less than the value of the variable on the right, the result is //TRUE//, otherwise //FALSE//. |
- | * < = (less than or equal to) | + | * < = (less than or equal to) - if the value of the variable on the left is less than or equal to the value of the variable on the right, the result is //TRUE//, otherwise //FALSE//. |
- | * > (greater than) - | + | * > (greater than) - if the value of the variable on the left is greater than the value of the variable on the right, the result is //TRUE//, otherwise //FALSE//. |
- | * > = (greater than or equal to) - | + | * > = (greater than or equal to) - if the value of the variable on the left is greater than or equal to the value of the variable on the right, the result is //TRUE//, otherwise // |
+ | |||
+ | Examples: | ||
+ | <code c> | ||
+ | if (x==y){ //equal | ||
+ | // | ||
+ | } | ||
+ | |||
+ | if (x!=y){ //not equal | ||
+ | // | ||
+ | } | ||
+ | |||
+ | if (x<y){ //less than | ||
+ | // | ||
+ | } | ||
+ | |||
+ | if (x<=y){ //less than or equal | ||
+ | // | ||
+ | } | ||
+ | |||
+ | if (x>y){ //greater than | ||
+ | // | ||
+ | } | ||
+ | |||
+ | if (x>=y){ //greater than or equal | ||
+ | // | ||
+ | } | ||
+ | </ | ||
==== Boolean operators ==== | ==== Boolean operators ==== | ||
- | The Boolean logical operators | + | Three Boolean logical operators |
- | * ! (logical | + | * ! (logical |
- | * && (logical | + | * && (logical |
- | * || (logical | + | * || (logical |
+ | Examples: | ||
+ | <code c> | ||
+ | //logical NOT | ||
+ | if (!a) { //the statement inside " | ||
+ | b = !a; //the reverse logical value of " | ||
+ | } | ||
+ | //logical AND | ||
+ | if (a && b){ //the statement inside " | ||
+ | //statement | ||
+ | } | ||
- | ===== Switch ===== | + | //logical OR |
- | Switch...case | + | if (a || b){ //the statement inside " |
+ | // | ||
+ | } | ||
+ | </ | ||
+ | ===== Switch case statement ===== | ||
+ | Switch statement similar like //if// statement controls the flow of program. The code inside //switch// is executed in various conditions. A //switch// statement compares the values of a variable to the specified values in the //case// statements. Allowed data types of the variable are //int// and //char//. The //break// keyword exits the //switch// statement. | ||
+ | Examples: | ||
+ | <code c> | ||
+ | switch (x) { | ||
+ | case 0: //executes when the value of x is 0 | ||
+ | // statements | ||
+ | | ||
+ | case 1: //executes when the value of x is 1 | ||
+ | // statements | ||
+ | | ||
+ | | ||
+ | // statements | ||
+ | | ||
+ | } | ||
+ | </ | ||
+ | |||
+ | |||
+ | **Check yourself** | ||
+ | 1. Which code part is correct? | ||
+ | |||
+ | * if (value == 1) digitalWrite(13, | ||
+ | * if (value == 1); digitalWrite(13, | ||
+ | * if (value == 1) DigitalRead(13, | ||
+ | 2. What is the output of the next code part? | ||
+ | |||
+ | <code c> | ||
+ | int x = 0; | ||
+ | |||
+ | switch(x) | ||
+ | { | ||
+ | |||
+ | case 1: cout << " | ||
+ | |||
+ | case 0: cout << " | ||
+ | |||
+ | case 2: cout << " | ||
+ | |||
+ | } | ||
+ | </ | ||
+ | 3. In which cases ' |