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#ifndef UTOA_H
#define UTOA_H
#include <string>
#include <cstring>
#ifndef DIGIT_LOOKUP_TABLE
# define DIGIT_LOOKUP_TABLE 0
#endif
const unsigned utoa_bufsize=21;
const unsigned utoa_bufsizem1=utoa_bufsize-1;
#ifdef DIGIT_LOOKUP_TABLE
namespace {
char digits[] = "0123456789";
}
#endif
inline char digit_to_char(int d) {
return
#ifdef DIGIT_LOOKUP_TABLE
digits[d];
#else
'0'+d;
#endif
}
// returns n in string [return,num); *num=0 yourself before calling if you want a c_str
inline char *utoa(char *num,unsigned n) {
if ( !n ) {
*--num='0';
} else {
unsigned rem;
// 3digit lookup table, divide by 1000 faster?
while ( n ) {
#if 1
rem = n;
n /= 10;
rem -= 10*n; // maybe this is faster than mod because we are already dividing
#else
rem = n%10; // would optimizer combine these together?
n = n/10;
#endif
*--num = digit_to_char(rem);
}
}
return num;
}
inline char *itoa(char *p,int n) {
if (n<0) {
p=utoa(p,-n); // TODO: check that (unsigned)(-INT_MIN) == 0x1000000 in 2s complement and not == 0
*--p='-';
return p;
} else
return utoa(p,n);
}
inline std::string utos(unsigned n) {
char buf[utoa_bufsize];
char *end=buf+utoa_bufsize;
char *p=utoa(end,n);
return std::string(p,end);
}
inline std::string itos(int n) {
char buf[utoa_bufsize];
char *end=buf+utoa_bufsize;
char *p=itoa(end,n);
return std::string(p,end);
}
//returns position of '\0' terminating number written starting at to
inline char* append_utoa(char *to,unsigned n) {
char buf[utoa_bufsize];
char *end=buf+utoa_bufsize;
char *s=utoa(end,n);
int ns=end-s;
std::memcpy(to,s,ns);
to+=ns;
*to++=0;
return to;
}
//returns position of '\0' terminating number written starting at to
inline char* append_itoa(char *to,unsigned n) {
char buf[utoa_bufsize];
char *end=buf+utoa_bufsize;
char *s=itoa(end,n);
int ns=end-s;
std::memcpy(to,s,ns);
to+=ns;
*to++=0;
return to;
}
#endif
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