How i convert char array to HEX

array 'data_value[1]' & array 'data_value[2]' have the temperature and Humidity value.

Does it mean:

1. The following array elements contain Temperature Data

data_value[1][0]
data_value[1][1]
-------------------
data_value[1][9]        //you have 10x10 character array;

Each array element contains 1-byte ASCII code for a HEX-digit; now, you combine two elements to get 1-byte HEX number. You have 10 elements (array members); after processing, you will get 5-byte data for the Temperature value. How to interpret this 40-bit data to find Temperature value in decimal format, that you know.

2. The following array elements contain Humidity Data

data_value[2][0]
data_value[2][1]
-------------------
data_value[2][9]        //you have 10x10 character array;

Serial.println(data_value[1]);// this the array value for Temp; How i convert this value?

Do you know the meaning of the above instruction - what will it print? It is going to print the contents of the following array elements one after another.

data_valuw[1][0], ...., data_value[1][9]    //Temperature value in character format 
data_value[2][0], ...., data_value[2][9]    //Humidity value in character format

...
data_value[9][0], ...., data_value[9][9] //----

Now, create your array manually:

char data_value[10][10] =    {

{'x', 'x', ................, 'x'},              //data_value[0][0], ............, data_value[0][9]
{'x', 'x', ................, 'x'},              //data_value[1][0],............., data_value[1][9]  //Tempertaure
{'x', 'x', ................, 'x'},              //data_value[2][0],............., data_value[2][9]  //Humidity 
..................................                .......................................................................................
{'x', 'x', ................, 'x'}               //data_value[9][0],............., data_value[9][9]

};

Assume that:

data_value[1][0] = 0x31      //1     assume lower digit of the HEX byte
data_value[1][1] = 0x45      //E     assume upper digit of the HEX byte

How to extract E1 from the above two elements?

byte x = data_value[1][0];    // x = 0x31 = 30 + 01
if (x < 0x41)
{
  x = x - 0x30;      // x = 0x31 - 0x30 = 0x01 = 00000001
}

else
{
  x = x - 0x37              //
}

byte y = data_value[1][1];    // y = 0x45 
if (y < 0x41)
{
  y = y - 0x30;      //
  y = y << 4;         //
}

else
{
  y = y - 0x37;              //0x45 - 0x37 = 0x0E = 00001110
  y =  y << 4;              //y = 11100000          
}

x = x|y;                     //x = 00000001 | 11100000 = 11100001 = E1

Now, you can use for() looping construct to reduce the number of instructions.