错误提示如下，只要注释掉sprintf就不会报错。
linking...d:/rt-threadstudio/repo/extract/toolchain_support_packages/arm/gnu_tools_for_arm_embedded_processors/5.4.1/bin/../lib/gcc/arm-none-eabi/5.4.1/../../../../arm-none-eabi/lib/armv7-m\libg.a(lib_a-sbrkr.o): In function `_sbrk_r':sbrkr.c:(.text._sbrk_r+0xc): undefined reference to `_sbrk'collect2.exe: error: ld returned 1 exit statusmake: *** [makefile:58: rtthread.elf] Error 1"make -j4 all" terminated with exit code 2. Build might be incomplete.
nano