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### Topic: 'For' Loop (Read 1 time)previous topic - next topic

#### panosip

##### Mar 18, 2013, 04:49 pmLast Edit: Mar 18, 2013, 04:52 pm by panosip Reason: 1
Hello.
I use 7 ultrasonic sensors for a project.
I want when ultrasonic sensor is out of range (returning int: 0) to make its value '100' instead of '0' (default)
I notice that the program doesn't function as expected. Still returns '0'

The  senB, senBL, senBR, senML, senMR, senL, senR, has for value, the detected distance for each sensor

Here is the code.

Code: [Select]
`      int convert[7] = {senB, senBL, senBR, senML, senMR, senL, senR};                                // If distance = 0  ->  distance = 100      temp = 100;                                                            for(int i = 0; i == 6; i++) {                                      if(convert[i] == 0) {                                            convert[i] = temp;                    }      }    `

Any suggestions?
Thanks

#### wildbill

#1
##### Mar 18, 2013, 04:53 pm
This:
Code: [Select]
`  for(int i = 0; i == 6; i++) `

was likely intended to be:
Code: [Select]
`  for(int i = 0; i <= 6; i++) `

#### panosip

#2
##### Mar 18, 2013, 05:01 pm

I am still getting '0' instead of '100'

#### panosip

#3
##### Mar 18, 2013, 05:05 pm
This is the part of the code that I use

Code: [Select]
`    NewPing sB(TRIGGER_PIN_B, ECHO_PIN_B, distance);           NewPing sBL(TRIGGER_PIN_BL, ECHO_PIN_BL, distance);        NewPing sBR(TRIGGER_PIN_BR, ECHO_PIN_BR, distance);      NewPing sML(TRIGGER_PIN_ML, ECHO_PIN_ML, distance);           NewPing sMR(TRIGGER_PIN_MR, ECHO_PIN_MR, distance);           NewPing sL(TRIGGER_PIN_L, ECHO_PIN_L, distance);           NewPing sR(TRIGGER_PIN_R, ECHO_PIN_R, distance);        unsigned int SDB = sB.ping();            unsigned int SDBL = sBL.ping();          unsigned int SDBR = sBR.ping();          unsigned int SDML = sML.ping();          unsigned int SDMR = sMR.ping();         unsigned int SDL = sL.ping();           unsigned int SDR = sR.ping();             senB = SDB / US_ROUNDTRIP_CM;            senBL = SDBL / US_ROUNDTRIP_CM;          senBR = SDBR / US_ROUNDTRIP_CM;             senML = SDML / US_ROUNDTRIP_CM;             senMR = SDMR / US_ROUNDTRIP_CM;             senL = SDL / US_ROUNDTRIP_CM;       senR = SDR / US_ROUNDTRIP_CM;       if (senB == 0 && senBL == 0 && senBR == 0 && senML == 0 && senMR == 0 && senL == 0 && senR == 0) {      // Check if sensors don't detect anything      enabled = 7;          }     else {          int convert[7] = {senB, senBL, senBR, senML, senMR, senL, senR};                                // If distance = 0  ->  distance = 100      temp = 100;                                                            for(int i = 0; i <= 6; i++) {                                      if(convert[i] == 0) {                                             convert[i] = temp;                    }      }                  Serial.print(senB); // for debug}`

#### Arrch

#4
##### Mar 18, 2013, 05:13 pm
Quote

I am still getting '0' instead of '100'

Not surprising, considering all this code:

Code: [Select]
`      int convert[7] = {senB, senBL, senBR, senML, senMR, senL, senR};                                // If distance = 0  ->  distance = 100      temp = 100;                                                            for(int i = 0; i <= 6; i++) {                                      if(convert[i] == 0) {                                             convert[i] = temp;                    }      }`

Is doing is replacing any 0 value in your array with 100. I think this assignment is backwards:

Code: [Select]
`convert[i] = temp;  `

#### kf2qd

#5
##### Mar 18, 2013, 05:19 pm
Is the variable temp getting changed somewhere else? temp is really a lousy name in this case because it is really being used as a constant. Better name would be something like hundred or cent.

#### panosip

#6
##### Mar 18, 2013, 05:27 pmLast Edit: Mar 18, 2013, 05:29 pm by panosip Reason: 1
So..I change the code to something like that

Code: [Select]
`    int convert[7] = {senB, senBL, senBR, senML, senMR, senL, senR};                                                                               for(int i = 0; i <= 6; i++) {                                   if(convert[i] == 0) {                                          convert[i] = 100;                 }   }`

value for senB remains '0'

EDIT:

I tried this code instead :
Code: [Select]
`  int convert[7] = {senB, senBL, senBR, senML, senMR, senL, senR};                                                                               for(int i = 0; i <= 6; i++) {                                     convert[i] = 100;               }`

Still nothing:(

#### majenko

#7
##### Mar 18, 2013, 05:32 pm
I'm not surprised.  This is not doing what you think:
Code: [Select]
`      int convert[7] = {senB, senBL, senBR, senML, senMR, senL, senR};                                // If distance = 0  ->  distance = 100      temp = 100;                                                            for(int i = 0; i <= 6; i++) {                                      if(convert[i] == 0) {                                             convert[i] = temp;                    }      }                  Serial.print(senB); // for debug`

What it is actually doing is:

1. Copy the values from the ping sensors' readings into the array.
2. Modify the contents of the array
3. Display one ping sensor's value

At no point are you modifying the ping sensor's value, just the contents of the array.

Try printing convert[0] instead, and see what you get.

If you want to do it this way and modify the source variable, you will have to use pointers:
Code: [Select]
`      int *convert[7] = {&senB, &senBL, &senBR, &senML, &senMR, &senL, &senR};                                // If distance = 0  ->  distance = 100      temp = 100;                                                            for(int i = 0; i <= 6; i++) {                                      if(*(convert[i]) == 0) {                                             *(convert[i]) = temp;                    }      }                  Serial.print(senB); // for debug`
(untested).

#### panosip

#8
##### Mar 18, 2013, 05:37 pm
Thanks guys for your help

@majenko that works!!! Thanks so much.

#### panosip

#9
##### Mar 18, 2013, 07:01 pmLast Edit: Mar 18, 2013, 07:02 pm by panosip Reason: 1
Hello
Another problem comes up:(
Now, I have finally set up my sensors and when they are out of range, they return 100 (int).
I want to find the sensor which has detect an item closer from the other 6 sensors.

So the code is:

Code: [Select]
`    NewPing sB(TRIGGER_PIN_B, ECHO_PIN_B, distance);           NewPing sBL(TRIGGER_PIN_BL, ECHO_PIN_BL, distance);        NewPing sBR(TRIGGER_PIN_BR, ECHO_PIN_BR, distance);       NewPing sML(TRIGGER_PIN_ML, ECHO_PIN_ML, distance);           NewPing sMR(TRIGGER_PIN_MR, ECHO_PIN_MR, distance);           NewPing sL(TRIGGER_PIN_L, ECHO_PIN_L, distance);           NewPing sR(TRIGGER_PIN_R, ECHO_PIN_R, distance);        unsigned int SDB = sB.ping();            unsigned int SDBL = sBL.ping();          unsigned int SDBR = sBR.ping();          unsigned int SDML = sML.ping();          unsigned int SDMR = sMR.ping();          unsigned int SDL = sL.ping();            unsigned int SDR = sR.ping();            senB = SDB / US_ROUNDTRIP_CM;          senBL = SDBL / US_ROUNDTRIP_CM;          senBR = SDBR / US_ROUNDTRIP_CM;             senML = SDML / US_ROUNDTRIP_CM;             senMR = SDMR / US_ROUNDTRIP_CM;             senL = SDL / US_ROUNDTRIP_CM;       senR = SDR / US_ROUNDTRIP_CM;    int *convert[7] = {&senB, &senBL, &senBR, &senML, &senMR, &senL, &senR};                                      temp = 100;                                                            for(int i = 0; i <= 6; i++) {                                      if(*(convert[i]) == 0) {                                             *convert[i] = temp;                    }      }            int *sensor[7] = {&senB, &senBL, &senBR, &senML, &senMR, &senL, &senR};                                  temp1 = 100;                                                            for(int i = 0; i <= 6; i++) {                                      if(*(sensor[i]) < temp1) {                                             temp1 = *(sensor[i]);             sensor = i;                 }      }    }                               Serial.println(sensor);    delay(1000);`

instead of returning back the position of sensor in the array (0 - 6) it randomly returns numbers from '0' to '6'

#### majenko

#10
##### Mar 18, 2013, 07:17 pm
Code: [Select]
`          sensor = i;         `
sensor is the array containing the list of sensor values pointers.  Try using a different variable, like "closestSensor".

#### mistergreen

#11
##### Mar 18, 2013, 07:19 pm
Code: [Select]
`sensor = i;  `

doesn't make sense. 'sensor' is an array not an int var. Just create another in like closestSensor = i. That will save the index.
You probably don't need the sensor[]... it's identical to convert[]....

#### panosip

#12
##### Mar 18, 2013, 07:32 pm
@majenko @mistergreen

You are absolutely right..My mistake

Thanks for your help guys.

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