replacing characters in char array with integers

Using Arduino Programming Questions
2

Have a look at all the nice functions working on cStrings in stdlib.h and string.h

To build your buffer you could use sprintf(). It uses a lot of memory and alternative with strcat() and itoa() would take less memory but might be more complicated to get started with

char buffer[10]; // ensure it’s large enough for your largest message with 1 extra byte for the trailing NULL char ‘\0’
sprintf(buffer,”C.%d”, 32); // buffer will be “C.32”
sevseg.setChars(buffer);

We don’t recommend the String class but if you want a simple code (with risks depending on how you use this over time) then build a String and then ask for its c_str(), this is the cString buffer you need

String aCrappyString = String(“C.”) + String(32);  // “C.32”
sevseg.setChars(aCrappyString.c_str());