how to fix "converting to 'const String' from initializer list would use explicit constructor 'String::String(int, unsigned char)'" error in arduino

Question

Using an Arduino. I have this code to read a file line by line as a string. This string is then inserted into an http url string. Here is the code. All of this except 'File.....' and 'String addr1' go inside the loop

String addr1 = "https://docs.google.com/forms/.......................14=happy";
String sd_data;
File testfile; // these parts come before void setup()
testfile = SD.open("testdata.txt", FILE_READ); //goes in the loop
while (testfile.available()) {
sd_data = testfile.readStringUntil('\n');

sd_data.replace(' ', '+'); // replace spaces with +
addr1.replace('happy', sd_data);
}

I get this error converting to 'const String' from initializer list would use explicit constructor 'String::String(int, unsigned char)'

'happy' is an integer. Certainly code should be using a string "happy" - somehow. — chux - Reinstate Monica
' ' and '+' are char. Uncertain about Arduino replace(). — chux - Reinstate Monica

Noel DSouza Noel DSouza · Accepted Answer · 2018-05-30T20:28:15

I've solved the problem, delete

String addr1=.........

instead of

addr1.replace('happy', sd_data);

put

String var="https://docs.google.com/forms/.......................14="+sd_data;

how to fix "converting to 'const String' from initializer list would use explicit constructor 'String::String(int, unsigned char)'" error in arduino

1 Answers