ecvt_r - Linux

Overview

The ecvt_r function in C converts a floating-point number into a string using a given format. This format is a combination of a significant number of digits and an exponent, and is often used for scientific or engineering notation.

Syntax

int ecvt_r(double value, int ndigits, int *decpt, int *sign, char *buf, size_t bufsize);

Parameters

• value: Double-precision floating-point number to convert.
• ndigits: Number of significant digits to use in the resulting string.
• decpt: Pointer to an integer that will be set to the position of the decimal point in the resulting string.
• sign: Pointer to an integer that will be set to a negative value if the number is negative, zero if the number is zero, and a positive value if the number is positive.
• buf: Pointer to a buffer that will hold the resulting string.
• bufsize: Size of the buffer pointed to by buf.

Options/Flags

None

Examples

#include <stdio.h>
#include <stdlib.h>

int main() {
    double value = 123.456;
    int ndigits = 6;
    char buf[100];
    int decpt, sign;

    ecvt_r(value, ndigits, &decpt, &sign, buf, sizeof(buf));

    printf("%s\n", buf);  // Output: "1.23456e+02"
    return 0;
}

Common Issues

• The buffer provided must be large enough to hold the resulting string. If it is not, the function will return an error code.
• The number of significant digits specified must be greater than zero. If it is not, the function will return an error code.

Integration

The ecvt_r function can be used in combination with other functions to perform more complex tasks. For example, it can be used with the strtod function to convert a string representation of a floating-point number to a double-precision floating-point number.

Related Commands

• printf: Formats and prints data to a stream.
• fprintf: Formats and prints data to a file.
• sprintf: Formats and prints data to a string.