When I make the src file, the problem is:

Vostro-260s:~/download/KaKs_Calculator2.0/src$ make

g++ -O -o KaKs_Calculator KaKs_Calculator.cpp KaKs.cpp MSMA.cpp MYN.cpp base.cpp NG86.cpp LWL85.cpp LPB93.cpp GY94.cpp YN00.cpp -lstdc++ -lm

KaKs.cpp: In member function ‘bool KAKS::parseParameter(int, const char**)’:

KaKs.cpp:356:90: error: ‘strlen’ was not declared in this scope

if (genetic_codeNCODE || strlen(transl_table[2*(genetic_code-1)])0) {

^

MYN.cpp: In member function ‘virtual int MYN::GetKappa(std::string, std::string)’:

MYN.cpp:35:31: warning: converting to non-pointer type ‘double’ from NULL [-Wconversion-null]

double kdefault=2, nullValue=NULL;

^

base.cpp: In constructor ‘Base::Base()’:

base.cpp:65:24: warning: converting to non-pointer type ‘double’ from NULL [-Wconversion-null]

Si[i] = Vi[i] = L[i] = NULL;

^

base.cpp:72:46: warning: converting to non-pointer type ‘double’ from NULL [-Wconversion-null]

Ka = Ks = Sd = Nd = S = N = snp = t = kappa = NULL;

^

base.cpp: In member function ‘std::string Base::parseOutput()’:

base.cpp:479:13: warning: NULL used in arithmetic [-Wpointer-arith]

if (Si[0]!=NULL || Si[2]!=NULL || Si[4]!=NULL) { //Si[0], Si[2], Si[4]

^

base.cpp:479:28: warning: NULL used in arithmetic [-Wpointer-arith]

if (Si[0]!=NULL || Si[2]!=NULL || Si[4]!=NULL) { //Si[0], Si[2], Si[4]

^

base.cpp:479:43: warning: NULL used in arithmetic [-Wpointer-arith]

if (Si[0]!=NULL || Si[2]!=NULL || Si[4]!=NULL) { //Si[0], Si[2], Si[4]

^

base.cpp:490:13: warning: NULL used in arithmetic [-Wpointer-arith]

if (Vi[0]!=NULL || Vi[2]!=NULL || Vi[4]!=NULL) { //Vi[0], Vi[2], Vi[4]

^

base.cpp:490:28: warning: NULL used in arithmetic [-Wpointer-arith]

if (Vi[0]!=NULL || Vi[2]!=NULL || Vi[4]!=NULL) { //Vi[0], Vi[2], Vi[4]

^

base.cpp:490:43: warning: NULL used in arithmetic [-Wpointer-arith]

if (Vi[0]!=NULL || Vi[2]!=NULL || Vi[4]!=NULL) { //Vi[0], Vi[2], Vi[4]

^

GY94.cpp: In member function ‘int GY94::preProcess(const char*, const char*)’:

GY94.cpp:229:22: error: ‘strlen’ was not declared in this scope

com.ls = strlen(seq1);

^

GY94.cpp:238:23: error: ‘strcpy’ was not declared in this scope

strcpy(com.z[0], seq1);

^

YN00.cpp: In member function ‘virtual int YN00::GetKappa(std::string, std::string)’:

YN00.cpp:81:31: warning: converting to non-pointer type ‘double’ from NULL [-Wconversion-null]

double kdefault=2, nullValue=NULL, t;

^

make: *** [KaKs_Calculator] error.

What's the reason for the error and how can I solve it? Thank you!