cstdlib
atof, atoi, atol, strtod, strtof, strtols, strtol, strtoll, strtoul, strtoull, rand, srand, calloc, free, malloc, realloc, abort, atexit, exit, getenv, system, bsearch, qsort, abs, div, labs, ldiv, llabs, tlldiv, mblen, mbtowc, wctomb, mbstowcs, wcstombs
- atof、atoi、atol
cout<<atoi("546.1")<<endl;//546
cout<<atof("546.1")<<endl;//546.1
cout<<atol("546.1")<<endl;//546
- strtod, strtof, strtols, strtol, strtoll, strtoul, strtoull
不仅可以字符串转数字,还可以顺带进制转换!
string s;
char *c;
cout<<strtod("213.454mkomo",&c)<<endl; //213.454
cout<<c<<endl; //mkomo
cout<<strtof("213.454mkomo",&c)<<endl; //213.454
cout<<c<<endl; //mkomo
cout<<strtol("123456789.454mkomo",&c,3)<<endl;//5
cout<<c<<endl; //3456789.454mkomo
cout<<strtoll("213.454mkomo",&c,10)<<endl; //213
cout<<c<<endl; //.454mkomo
cout<<strtoul("213.454mkomo",&c,10)<<endl; //213
cout<<c<<endl; //.454mkomo
- rand、srand
srand((unsigned)time(0));
cout<<rand()<<endl;
- abs、labs
cout<<abs(-45.67)<<endl;//45.67
cout<<labs(-45.67)<<endl;-45.67
cmath
- pow
cout<<pow(2,3)<<endl;//8
- sqrt
- fabs
cout<<fabs(-45.67)<<endl;//45.67