Read Line By Line Until Integer is Found C - c

Question

Trying to create a program that takes in a text file and reads it line by line. It then finds the two integers that are on each line and adds them together. It then outputs the new line with the original string and total to a new text file. I need help adding the two integers, getting them from each line, and then putting the new line to a text file.
input text file
good morning hello 34 127
ann 20 45
10 11
fun program and you find the same 90 120
news paper said that 56 11
how do you like 20 5
line number 90 34
Outputs first like would look like: and then continue on
good morning hello 161
Code:
int processTextFile(char * inputFileName, char * outputFileName)
{
FILE *fp = fopen(inputFileName, "r");//open file to to read
char buff[1024];
char *p, *p1;
int num;
while (fgets(buff, 1024, fp)!=NULL)
{
printf("%s\n", buff);
while(scanf(buff, "%*[^0-9]%d", &num)== 1)
printf("%d\n", num);
//fscanf(fp, "%s", buff);
}
return 0;
}
EDIT!!!!::
So now that I've been able to accomplish this. How would I sort it by the number produced? for example:
Time is money 52
here I am 3
21
Would output to a new text file in order like
here I am 3
21
Time is money 52

Answer 1

My version using strcspn() is supposed to work with stdin for input and stdout for output. (so you can do executable <textfile >newtextfile)
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(void) {
char line[1000];
while (fgets(line, sizeof line, stdin)) {
char *ptr;
size_t x = strcspn(line, "0123456789");
if (line[x]) {
errno = 0;
int n1 = strtol(line + x, &ptr, 10);
if (*ptr && !errno) {
errno = 0;
int n2 = strtol(ptr, &ptr, 10);
if (*ptr && !errno) {
int n3 = n1 + n2;
printf("%.*s%d\n", (int)x, line, n3);
} else {
printf("%s", line); // line includes ENTER
}
} else {
printf("%s", line); // line includes ENTER
}
} else {
printf("%s", line); // line includes ENTER
}
}
return 0;
}
The same version without the error checking
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(void) {
char line[1000];
while (fgets(line, sizeof line, stdin)) {
char *ptr;
size_t x = strcspn(line, "0123456789");
int n1 = strtol(line + x, &ptr, 10);
int n2 = strtol(ptr, &ptr, 10);
int n3 = n1 + n2;
printf("%.*s%d\n", (int)x, line, n3);
}
return 0;
}

Answer 2

The approach should be:
open two files, one for input, one for output.
use sscanf() to read the input buffer.
scan the leading string, and then two number.
if previous sscanf() fails, only check for two number.
if either of the above scanning is success, print the sum to the output file.
A sample code, should look like
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(void)
{
FILE *fpin = fopen("ipfile", "r");//open file to to read
if (!fpin)
{
printf("Error in ipfile opening\n");
exit (-1);
}
FILE *fpout = fopen("opfile", "w");//open file to to write
if (!fpout)
{
printf("Error in opfile opening\n");
exit (-1);
}
char buff[1024] = {0};
char str[1024] = {0};
int num1 =0, num2= 0;
while (fgets(buff, 1024, fpin)!=NULL)
{
memset(str, 0, sizeof(str));
//printf("%s\n", buff);
if(sscanf(buff, "%[^0-9]%d %d", str, &num1, &num2)== 3)
fprintf(fpout, "%s %d\n", str, (num1+num2));
else if (sscanf(buff, "%d %d", &num1, &num2)== 2)
fprintf(fpout, "%d\n", (num1+num2));
}
return 0;
}
Note:
The above procedure, is a kind of workaround. If the data pattern in the file changes, lot of changes will be required to maintain a code like that. Instead of usinf sscnaf(), for a better and roubust approach, you should
read the line from file
start tokenizing the input buffer (strtok()) and check for ints as tokens (strtol()).
save the returned tokens and ints seperately.
once the strtok() returns NULL, you print the string tokens and the sum of the ints to the o/p file.

Answer 3

I intend not to change your code completely, so I just added some snippets for improvement.
int processTextFile(char *inputFileName, char *outputFileName) {
FILE *fp = fopen(inputFileName, "r");
FILE *out = fopen(outputFileName, "w");
char line[1024];
if (!fp) {
perror(inputFileName);
return;
}
while (fgets(line, sizeof(line), fp) != NULL) {
int num1 = 0, num2 = 0;
char textPart[1024] = "";
if ( !sscanf(line, "%[a-zA-Z' ']%d%d", textPart, &num1, &num2) {
sscanf(line, "%d%d", &num1, &num2);
}
fprintf(out, "%s %d\n", textPart, num1 + num2);
}
fclose(fp);
fclose(out);
}
Explanation:
I scanned the text file, extracted the text part and the two ints. Since I noticed that the ints are placed at the end of each line, I just used sscanf() for that matter.
sscanf(line, "%[a-zA-Z' ']%d%d", textPart, &num1, &num2);
Here, "%[a-zA-Z' ']%d%d" format specifiers means to get only alphabets and spaces.
Since it will only get letters and spaces, the line "10 11" in your input file won't be put to num1 and num2. Because the code inspects first for a string containing letters and spaces. Since 10 and 11 are not of the qualified types, then the line is just skipped.
That's why I added an if-else statement, which checks if sscanf wrote anything to memory. If sscanf returned 0, then it means that no text part is present. Just digits. So the program will scan the two digits.
if ( !sscanf(line, "%[a-zA-Z' ']%d%d", textPart, &num1, &num2) ) {
sscanf(line, "%d%d", &num1, &num2);
}
I also added file checking for input file. It checks if file doesn't exist or can't be opened by the filestream.
if (!fp) {
perror(inputFileName);
return;
}
Here is the content of output file after execution:
good morning hello 161
ann 65
21
fun program and you find the same 210
news paper said that 67
how do you like 25
line number 124