atoi itoa

int atoi ( const char * str );

Convert string to integer

Example
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/* 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;}


Output:
Enter a number: 73The value entered is 73. The double is 146.

See also
atol
Convert string to long integer (function )
atof
Convert string to double (function )
strtol
Convert string to long integer (function )
[itoa]
char *  itoa ( int value, char * str, int base );
Convert integer to string (non-standard function)

Portability
This function is not defined in ANSI-C and is not part of C++, but is supported by some compilers.

A standard-compliant alternative for some cases may be sprintf:
sprintf(str,"%d",value) converts to decimal base.
sprintf(str,"%x",value) converts to hexadecimal base.
sprintf(str,"%o",value) converts to octal base.

Example
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/* 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;}


Output:
Enter a number: 1750decimal: 1750hexadecimal: 6d6binary: 11011010110

See also
sprintf
Write formatted data to string (function )
atoi
Convert string to integer (function )
atol
Convert string to long integer (function )



转自：

http://www.cplusplus.com/reference/clibrary/cstdlib/strtol/