For fixed strings (which do not change), use e.g. F("Text") ... this will place the string in flash instead of heap space. Note that the Uno has 32 KB of flash and 2 KB of SRAM (which is used for heap space among others).

If you need variable sized strings but one or few at a time, make a dedicated buffer (of e.g. 64 bytes) and use that buffer for all string operations. It will take up 64 bytes all time, but will leave no heap gaps. You can create it as a global variable (simple):

char string_buffer[64];

and use that string_buffer for string operations.

For fixed strings (which do not change), use e.g. F("Text") ... this will place the string in flash instead of heap space. Note that the Uno has 32 KB of flash and 2 KB of SRAM (which is used for heap space among others).

If you need variable sized strings but one or few at a time, make a dedicated buffer (of e.g. 64 bytes) and use that buffer for all string operations. It will take up 64 bytes all time, but will leave no heap gaps. You can create it as a global variable (simple):

char string_buffer[64];

and use that string_buffer for string operations.

Note that heap gaps are bad for all devices/operating systems, however since the Arduino has very little builtin SRAM, it is filledup quickly when using strings without thinking about memory management.