C/Cplusplus some functions
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One-atoi:<stdlib.h> /*atoi example*/ #include <stdio.h> #include <stdlib.h> int main () { int i; char szInput [256]; printf ("Enter a number: "); fgets ( szInput, 256, stdin ); i = atoi (szInput); printf ("The value entered is %d. The double is %d.\n",i,i*2); return 0; } Two-itoa:<stdlib.h> // itoa example #include <stdio.h> #include <stdlib.h> int main () { int i; char buffer [33]; printf ("Enter a number: "); scanf ("%d",&i); itoa (i,buffer,10); printf ("decimal: %s\n",buffer); itoa (i,buffer,16); printf ("hexadecimal: %s\n",buffer); itoa (i,buffer,2); printf ("binary: %s\n",buffer); return 0; } Three-char->string&&string->char: #include <iostream> #include <string> using namespace std; int main() { string x,temp; char p[15]="i am a boy!"; cin>>x; cout<<x.c_str()<<endl; temp=p; cout<<temp<<endl; return 0; } Four-sprintf(Formatted data to writing a string)<stdio.h> #include <iostream> #include <stdio.h> using namespace std; int main() { char str[20]; sprintf(str,"%d",168); cout<<str<<endl; sprintf(str,"��",123,457); cout<<"Specified width"<<str<<endl; sprintf(str,"%8x",123); cout<<"width+hexadecimal"<<str<<endl; return 0; } Five-ceil(返回大于或者等于指定表达式的最小整数) // ceil example #include <stdio.h> #include <math.h> int main () { printf ("ceil of 2.3 is %.1lf\n", ceil (2.3) ); printf ("ceil of 3.8 is %.1lf\n", ceil (3.8) ); printf ("ceil of -2.3 is %.1lf\n", ceil (-2.3) ); printf ("ceil of -3.8 is %.1lf\n", ceil (-3.8) ); return 0; } Output: ceil of 2.3 is 3.0 ceil of 3.8 is 4.0 ceil of -2.3 is -2.0 ceil of -3.8 is -3.0 |