Replace String with char* to copy in an array from SD card

Projects Programming
1

I would like to replace String with char*. (I don't want to use Progmem to free SRAM space). After some research, I know that I have to use strcpy and something different than readStringUntil('\n') but I have difficulties to put everything in a right way.

This code is working but I have (of course) memory problem when the number of lines in my file text is high (I have 7000 lines in the file I'd like to use).

int i=0;
File printFile;  
String tableau[100];   // I know the exact number of lines in the file

printFile = SD.open("/test.txt");

if (!printFile) {
  Serial.print("The text file cannot be opened");
  while(1);
}

while (printFile.available()) {

 tableau[i]= printFiletop100g.readStringUntil('\n');

  i++;
}

printFileprenombretong.close();

Here the code with lots of mistakes

File printFile; 
char *pointeur = NULL;
char tab[20];
int numberLines=10000;
int i=0;

printFile = SD.open("/test.txt");

if (!printFile) {
  Serial.print("The text file cannot be opened");
  while(1);
  }


pointeur =malloc(numberLines * sizeof(char*));

for(i = 0; i < numberLines; i++)
 {

    pointeur[i] = malloc((strlen(rareg) + 1) * sizeof(char));
    strcpy(pointeur[i],tab);
    i++;
}

printFile.close();

// Then the free pointeur function.

A file txt looks like :

Hello
How are You
Good
12Years
Why
...
In the end I'd like pointer[0]="Hello" pointer[1]="How are you" ...


Thanks for your help.
2

7000 lines will take a lot of memory. Which Arduino are you using?

3

Hello

A lolinD32 PRo
SoC : ESP32-WROVER @ 240MHz avec 4Mo de mémoire 4 Mo et 4Mo de PSRAM