1.
用 math库
错误信息:
/tmp/ccmJmMoE.o: In function `test':
test.c:(.text+0x19): undefined reference to `log10'
collect2: ld returned 1 exit status
gcc -Wall main.o test.o -lm -o test
-lm 要放到 .o 后面
2.
libssl
libssl.so: undefined reference to `BN_CTX_free'
libssl.so: undefined reference to `X509_free'
...
编译时加上 ssl 和 crypto 两个
-lssl -lcrypto