gcvt - Convert a floating-point number to a string

Definition	#include <stdlib.h> char *gcvt(double value, int n, char *buf); gcvt converts a floating-point number value to a string of digits and stores the string in the area pointed to by buf. A pointer to this area is returned as a result. Depending on the structure of the floating-point value to be converted, the output format corresponds to the FORTRAN F format: n significant digits, no leading or trailing zeros from value, a negative sign if required, and a decimal point (if there are any non-zero digits after the decimal point) or the FORTRAN E format (exponential notation).
Parameters	double value Floating-point value to be edited for output. int n Number of digits in the resulting string (calculated as of the first non-zero digit in the floating-point value to be converted). If n is less than the number of digits in value, the least significant digit is rounded. If n is greater, the string ends with the last non-zero digit. char *buf Pointer to the converted string. The memory area to which buf points should be at least (n + 4) bytes in size!
Return val.	Pointer to the converted string. gcvt terminates the string with the null byte (\0).
Notes	Invalid parameters, such as an integer instead of a double value, cause the program to abort! It is your responsibility to ensure that the result pointer buf points to a memory area of at least (n + 4) bytes (see example).
Example	The program reads a floating-point value x, converts it as specified in n, and outputs it as a string to the char array buf. The malloc function is used to reserve (n + 4) bytes. #include <stdio.h> #include <stdlib.h> int main(void) { double x; int n; char *buf; printf("Please enter floating-point number: \n"); if ( scanf("%lf",&x) == 1) { printf("How many significant digits : \n"); if ( scanf("%d",&n) == 1) { buf = (char *)malloc(n + 4); printf("After conversion, the number is : %s \n", gcvt(x, n, buf)); } } return 0; }
See also	ecvt, gcvt