#include <stdio.h>
#include <stdlib.h> // exit
#include <string.h> // strlen
#include <ctype.h> // isdigit
// Function to replace a digit at a given position in a floating-point number
double replaceFloatDigit(double number, size_t position, char newDigit) {
// Validate that newDigit is indeed a digit
if (!isdigit((unsigned char)newDigit)) {
fprintf(stderr, "Replacement must be a digit (0-9).\n");
exit(EXIT_FAILURE);
}
// Convert number to string with enough precision to preserve digits
char strNum[64];
snprintf(strNum, sizeof(strNum), "%.10f", number); // Adjust precision as needed
// Validate position
if (position >= strlen(strNum)) {
fprintf(stderr, "Position is out of range for the number string.\n");
exit(EXIT_FAILURE);
}
// Replace the digit (skip if it's a decimal point or minus sign)
if (strNum[position] == '.' || strNum[position] == '-') {
fprintf(stderr, "Position points to a non-digit character.\n");
exit(EXIT_FAILURE);
}
strNum[position] = newDigit;
// Convert back to double
return strtod(strNum, NULL);
}
int main() {
double num = 89710.291;
size_t pos = 2; // position to replace (0-based index)
char newDigit = '8';
double result = replaceFloatDigit(num, pos, newDigit);
printf("Modified number: %.3f\n", result);
return 0;
}
/*
run:
Modified number: 89810.291
*/
