How to convert a char to int in Arduino

Question

I receive some data in a char variable, and the result in teststring is always a number. How can I convert this number to a variable int?

After that I can put the int variable on delay time. There is a piece of my code:

String readString = String(30);
String teststring = String(100);
int convertedstring;

teststring = readString.substring(14, 18); (Result is 1000)

digitalWrite(start_pin, HIGH);
delay(convertedstring); // Result of teststring convert
digitalWrite(start_pin, LOW);

Solution

Use:

long number = atol(input); // Notice the function change to atoL

Or, if you want to use only positive values:

Code:

unsigned long number = strtoul(input, NULL, 10);

Reference: http://www.mkssoftware.com/docs/man3/atol.3.asp

Or,

int convertedstring = atoi(teststring.c_str());

Comments

[milhas]

Error: cannot convert 'String' to 'const char*' for argument '1' to 'int atoi(const char*)'

[milhas]

That's my try: long number = atol( teststring );

[Bouraoui KACEM]

stackoverflow.com/questions/11776210/… it can help you

[Bouraoui KACEM]

also this link is usefull : forum.arduino.cc/index.php/topic,103511.0.html

[milhas]

It-s working! int convertedstring = atoi(teststring.c_str()); Tnk you

[ohhorob]

Looks like you might have a bug where the pointer s is always incremented even when the first character is not '-'?

[Peter Mortensen]

What do you mean by "String to Long Arduino IDE"?