Splitting a string from a input without using strtok() - c

Question

I have been working on a program to read zip codes and populations from a .csv file and find the zip code with the largest and smallest population. I'm tasked to do this without using scanf(all variants) and strtok(). Currently, it outputs the entire string and I do not know how to split the string into just zip code and population. Any help is appreciated.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(){
int lines = 1024; //Maximum lines, specified
char str[256]; //Maximum characters, specified
char* pEnd = str;
//Variables for parsing data
char zipCode[256];
char population[256];
long bufPopulation = 0; //Variable to convert from string to long
//Variables to track the number of zipcodes and total population
static int NumOfZipCodes = 0;
static long totalPopulation = 0;
for (int i = 0; i < lines && fgets(str, sizeof(str), stdin); i++){
//parses the data being read into variable 'str'
strcpy(zipCode, str);
strcpy(population, str);
printf("String %s", str); //outputs str
printf("Zip codes %s", zipCode); //outputs zipCode
printf("Population %s", population); //outputs population
if (i > 0){
bufPopulation = strtol(population, &pEnd, 10);
printf("Buffer population %.0ld", bufPopulation); //outputs the long value of population
totalPopulation += bufPopulation;
NumOfZipCodes++;
}
}
int size = sizeof population/sizeof population[0];
long maxPop, minPop = 0;
char maxZip, minZip = zipCode[0];
for (int i = 1; i < size; i++){
bufPopulation = strtol(population, &pEnd, 10);
if (minPop > bufPopulation)
{
minPop = bufPopulation;
minZip = zipCode[i];
}
if (maxPop < bufPopulation)
{
maxPop = bufPopulation;
maxZip = zipCode[i];
}
}
//Displays the stored values
printf("Total Population across %d zipcodes is ", NumOfZipCodes);
printf("%.0ld\n", totalPopulation);
printf("The fewest people live in %.0d, population ", minZip);
printf("%.0ld\n", minPop);
printf("The most people live in %.0d, population ", maxZip);
printf("%.0ld\n", maxPop);
return 0;
}

Answer 1

The strtol() function assigns endptr, which is pointed by the second
argument, to the address of the remaining string after converting the valid
substring into the long integer. The character pointed by the address will
be normally the delimiter or the newline character at the end of the string.
Then you can repeat calling strtod() and skipping the delimiter to parse
the columns of the csv line. Would you please try the following:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXCHARS 256 // max characters in a line
#define DELIM ' ' // column delimiter
int main() {
char str[MAXCHARS]; // line buffer
char *eptr; // pointer within str
int zip, minZip, maxZip;
long pop, minPop, maxPop;
int numOfZipCodes = 0;
long totalPopulation = 0;
fgets(str, MAXCHARS, stdin); // read the header and discard
while (fgets(str, MAXCHARS, stdin)) { // read each line
zip = (int)strtol(str, &eptr, 10); // parse the zip code
if (*eptr != DELIM) { // check the next delimiter
fprintf(stderr, "illegal input string: %s", str);
exit(1);
}
while (*eptr == DELIM) eptr++; // skip the delimiter
pop = strtol(eptr, &eptr, 10); // parse the population
if (*eptr != DELIM) { // check the next delimiter
fprintf(stderr, "illegal input string: %s", str);
exit(1);
}
printf("Zip code %d\n", zip); // output zip code
printf("Population %ld\n", pop); // output population
if (numOfZipCodes == 0) { // initialize values on the 1st line
minPop = maxPop = pop;
minZip = maxZip = zip;
} else {
if (minPop > pop) {
minPop = pop;
minZip = zip;
}
if (maxPop < pop) {
maxPop = pop;
maxZip = zip;
}
}
totalPopulation += pop;
numOfZipCodes++;
}
// display the results
printf("Total Population across %d zipcodes is %ld\n", numOfZipCodes, totalPopulation);
printf("The fewest people live in %d, population %ld\n", minZip, minPop);
printf("The most people live in %d, population %ld\n", maxZip, maxPop);
return 0;
}
It assumes the delimiter is a whitespace as shown in your comment. If the
deimiter is a comma or other character, modify the #define DELIM ' ' line
accordingly.