Strcat (with MRE)

Projects Programming
1 
char gLog [5];
char gCode[3];

byte idx;

void setup() {
  Serial.begin(19200);
  gCode = "E";
}

void loop() {
  for(idx = 0; idx < 3; idx ++)
  {
    strcat(gLog, gCode);
    Serial.println(gLog);
    delay(2000);
  }

  gLog = "";  // blank gLog, start over
}

Desired / Anticipated Result:

E
EE
EEE
E  // and so on ...

Verify/Compile --
incompatible types in assignment of 'const char [2]' to 'char [3]'

I don't get it.

2

C/C++ does not allow copying one array to another using "=". Instead,

strcpy(gCode,"E");

To use strcat, assuming gCode is initialized to zero,

strcat(gCode,"E");
Serial.println(gCode);  //should print E
strcat(gCode,"E");
Serial.println(gCode); //should print EE
3 
strcpy(gCode, "E");
4

@jremington and @sterretje
Thank You.

char gLog [5];
char gCode[3];

byte idx;

void setup() {
  Serial.begin(19200);
  strcpy (gCode, "E");
}

void loop() {
  for(idx = 0; idx < 3; idx ++)
  {
    strcat(gLog, gCode);
    Serial.println(gLog);
    delay(2000);
  }

  strcpy (gLog, "");  // blank gLog 
}
5

I thought strNcat was advised in Arduino c++ code over strcat... (and strncpy ... et c.)

6

It is indeed. The OP and other readers are hereby reminded that this construction can safely contain a C-string consisting of only two ASCII characters, plus the terminating zero.

char gCode[3];
7

Although not part of the C standard library, the 'l' versions (strlcat() and strlcpy()) are considered safer as you always pass the full size of the destination buffer.