strtok problem while parsing String

Question 1

Here is my code. The incoming string is "*CRB12344,Temp25,Humidity55,CC5#"

I am unable to get value of Temp which is 25 and Humidity which is 55 and CC which 5. It only display the value of CR i.e B12344 (in this case). May be issue with strtok function?

String inputString = "";boolean stringComplete = false, StartCapturing = false;char inData[50];char inChar, IncomingWeight;char IncomingString[50];const int httpPort = 80;char *i, *k,*p;String CardID;int Temprature, Humidity, TC, CC;byte SendData = 0;void setup(){  Serial.begin(9600);}void loop(){  serialEvent();  if (stringComplete)  {    inputString.toCharArray(IncomingString, 50);    Serial.println();    Serial.println(IncomingString);    i = strstr(IncomingString, "CR");    {      if (i)      {        p = i+2;        CardID = strtok(p, ",");        Serial.print("Card Number :");        Serial.print(CardID);        Serial.println();      }    }    i = strstr(IncomingString, "Temp");    {      if (i)      {        Temprature = strtoul(i + 4 , NULL, 10);        Serial.print("Temprature :");        Serial.print(Temprature);        Serial.println();      }    }    i = strstr(IncomingString, "Humidity");    {      if (i)      {        Humidity = strtoul(i + 8 , NULL, 10);        Serial.print("Humidity :");        Serial.print(Humidity);        Serial.println();      }    }    i = strstr(IncomingString, "TC");    {      if (i)      {        TC = strtoul(i + 2 , NULL, 10);        Serial.print("Total Count :");        Serial.print(TC);        Serial.println();      }    }    i = strstr(IncomingString, "CC");    {      if (i)      {        CC = strtoul(i + 2 , NULL, 10);        Serial.print("Current Count :");        Serial.print(CC);        Serial.println();      }    }    stringComplete = false;    inputString = "";    delay(10);  }

Question 2

strtok() is a destructive function. It replaces the token with an end-of-string marker (\0). Thus once used the original string is irevocably lost.

Your first use ofstrtok() changes the string from:

*CRB12344,Temp25,Humidity55,CC5#\0

to:

*CRB12344\0Temp25,Humidity55,CC5#\0

Thus any future references toInputString only see up to the end-of-string marker:

*CRB12344\0

Instead you should usestrtok() in awhile loop to slice the string into tokens and examine what the token is:

char *tok = strtok(IncomingString, ",");while (tok) {    if (strncmp(tok, "*CR", 3) == 0) { // tok is *CRB1234        // ... whatever ...    } else if (strncmp(tok, "Temp", 4) == 0) { // tok is Temp25        // ... whatever ...    } else if (strncmp(tok, "Humidity", 8) == 0) { // tok is Humidity55        // ... whatever ...    } else if (strncmp(tok, "CC", 2) == 0) { // tok is CC5#        // ... whatever ...     }    tok = strtok(NULL, ","); // Note: NULL, not IncomingString}

Question 3

Didn't know this. I understand the mistake now.

Majenko 106k5 gold badges82 silver badges139 bronze badges · Accepted Answer · 2016-11-12 11:35:26Z

strtok() is a destructive function. It replaces the token with an end-of-string marker (\0). Thus once used the original string is irevocably lost.

Your first use ofstrtok() changes the string from:

*CRB12344,Temp25,Humidity55,CC5#\0

to:

*CRB12344\0Temp25,Humidity55,CC5#\0

Thus any future references toInputString only see up to the end-of-string marker:

*CRB12344\0

Instead you should usestrtok() in awhile loop to slice the string into tokens and examine what the token is:

char *tok = strtok(IncomingString, ",");while (tok) {    if (strncmp(tok, "*CR", 3) == 0) { // tok is *CRB1234        // ... whatever ...    } else if (strncmp(tok, "Temp", 4) == 0) { // tok is Temp25        // ... whatever ...    } else if (strncmp(tok, "Humidity", 8) == 0) { // tok is Humidity55        // ... whatever ...    } else if (strncmp(tok, "CC", 2) == 0) { // tok is CC5#        // ... whatever ...     }    tok = strtok(NULL, ","); // Note: NULL, not IncomingString}

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strtok problem while parsing String

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