Using strstr to find four different partial words - c

Question

I am looking to find part of a string containing TP2, DP3, OP1, or OP2, in a text file.
On each line is a different set of characters and eventually these three characters are used, but they are never on the same line as each other.
I can get it to print once I find the OP2, but it will not print the three before it. If I comment out the OP2 it finds OP1 and if I do that to OP1 and OP2 it finds DP3 and so on.
I do not get why it cannot print out all four different ones once found.
I used two different methods one where I strcpy into a temp and one I just print it as is and neither work. Later I want it to print to the right of the = sign on the lines with the four search types, but I will work on that after I get the print issue fixed. Any help or reasons why would be much appreciated.
#include < stdio.h>
#include < stdlib.h>
#include < string.h>
#define MAX_LINE_LENGTH 150
int main(void) {
FILE *file1, *file2;
char parts[MAX_LINE_LENGTH+1];
int len = strlen(parts);
//char TP2[3] = "TP2";
char DP3[3] = "DP3";
char MOP1[3] = "OP1";
//char MOP2[3] = "OP2";
//char TP2Temp[MAX_LINE_LENGTH];
char DP3Temp[MAX_LINE_LENGTH];
char MOP1Temp[MAX_LINE_LENGTH];
//char MOP2Temp[MAX_LINE_LENGTH];
file1 = fopen("input.txt", "r");
file2 = fopen("output2.txt", "w");
if (file1 == NULL || file2 ==NULL) {
exit(1);
}
while(fgets(parts, sizeof(parts), file1)!=NULL){
if(parts[len -1 ] =='\n'){
parts[len -1 ] ='\0';
}
//if(strstr(parts, TP2)!=NULL){
// strcpy(TP2Temp, parts);
// fprintf(file2, "%s", TP2Temp);
//}
if(strstr(parts,DP3)!=NULL){
strcpy(DP3Temp, strstr(parts,DP3));
fprintf(file2, "%s", DP3Temp);
}
else if(strstr(parts, MOP1)!=NULL){
strcpy(MOP1Temp, strstr(parts,MOP1));
fprintf(file2, "%s", MOP1Temp);
}
/*else if(strstr(parts, MOP2)!=NULL){
strcpy(MOP2Temp, parts);
fprintf(file2, "%s", MOP2Temp);
}*/
}
fclose(file1);
fclose(file2);
return 0;
}
/*Here is the text file sample
TC_TP1[2]=1
TC_TP2[2]="9070036"
TC_TP3[2]=1
TC_TP4[2]=1
TC_TP5[2]=1
TC_TP6[2]=1
TC_TP7[2]=1
TC_DP1[2,1]=120
TC_DP2[2,1]=0
TC_DP3[2,1]=179.85
TC_DP4[2,1]=0
TC_DP5[2,1]=0
TC_MOP1[2,1]=3
TC_MOP2[2,1]=28
TC_MOP3[2,1]=0
TC_MOP4[2,1]=0
TC_TP1[3]=1
TC_TP2[3]="9005270"
TC_TP3[3]=1*/

Answer 1

char parts[MAX_LINE_LENGTH+1];
int len = strlen(parts);
parts is uninitialised in this code, and thus isn't guaranteed to contain a string. Even if it were to, len would be initialised the length of that garbage string, which is meaningless and thus useless.
char DP3[3] = "DP3";
If your understanding of strings is valid, you should realise there are four characters in these strings. The following program demonstrates this:
#include <stdio.h>
int main(void) {
printf("sizeof \"DP3\": %zu\n", sizeof "DP3");
}
You are reading a book to learn C, right? Your book would explain to you among many other things so we wouldn't need to, strstr requires its operands be strings, and strings always contain a terminating '\0'. Where's your terminating '\0'? How is strstr expected to know the length of the string pointed to by DP3?
Because the length of your tokens are at most three bytes, you currently only need to read and store at most three bytes at a time to conduct your search (four including the terminal byte explained above; untested&incomplete example below); this requirement could change, should you decide to introduce longer (or dynamically sized) tokens, your cursor will need to be as wide as your longest token.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef unsigned char item[4];
int item_cmp(void const *x, void const *y) {
return memcmp(x, y, sizeof (item));
}
int main(void) {
item cursor = "",
haystack[] = { "TP1", "OP0", "OP1", "OP2", "TP0", "DP3", "OOO" };
size_t size = fread(cursor, sizeof cursor - 1, 1, stdin),
nelem = sizeof haystack / sizeof *haystack;
int c = 0, e = !size;
qsort(haystack, nelem, sizeof *haystack, item_cmp);
do {
if (bsearch(cursor, haystack, nelem, sizeof *haystack, item_cmp)) {
printf("match found for %s\n", cursor);
}
memmove(cursor, cursor + 1, sizeof cursor - 1);
if (!e) {
c = fgetc(stdin);
e = c < 0 && feof(stdin);
}
cursor[size] = e || c == '\n' ? '\0' : c;
size -= e;
} while (size);
exit(0);
}

Answer 2

Thank you again BLUEPIXY, with your information I was able to make the changes I needed and was able to extract the data where it found TP2 and then the value after the equal sign. I am sure there is a nicer way to code this, but my solution is below. I will add a change to be able to take in any file name and the reason for the
MOP1Equal[strlen(MOP1Equal) -1] ='\0';
was to make it in columns for a csv file to put in excel and the
fprintf(file2, "\t%s", MOP1Equal+1);
where I add 1 was to get rid of the = sign.
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define MAX_LINE_LENGTH 150
int main(void) {
FILE *file1, *file2;
char parts[MAX_LINE_LENGTH+1] = "startingvaluebeforechange";
char TP2[4] = "TP2";
char DP3[4] = "DP3";
char MOP1[4] = "OP1";
char MOP2[4] = "OP2";
char Equal[2] = "=";
char TP2Temp[MAX_LINE_LENGTH];
char TP2Equal[MAX_LINE_LENGTH];
char DP3Temp[MAX_LINE_LENGTH];
char DP3Equal[MAX_LINE_LENGTH];
char MOP1Temp[MAX_LINE_LENGTH];
char MOP1Equal[MAX_LINE_LENGTH];
char MOP2Temp[MAX_LINE_LENGTH];
char MOP2Equal[MAX_LINE_LENGTH];
file1 = fopen("input.txt", "r");
file2 = fopen("output.txt", "w");
if (file1 == NULL || file2 ==NULL) {
exit(1);
}
while(fgets(parts, sizeof(parts), file1)!=NULL){
int len = strlen(parts);
if(parts[len -1 ] =='\n'){
parts[len -1 ] ='\0';
}
if(strstr(parts, TP2)!=NULL){
strcpy(TP2Temp, strstr(parts,TP2));
strcpy(TP2Equal, strstr(TP2Temp,Equal));
TP2Equal[strlen(TP2Equal) -2] ='\0';
fprintf(file2, "%s", TP2Equal+2);
}
if(strstr(parts,DP3)!=NULL){
strcpy(DP3Temp, strstr(parts,DP3));
strcpy(DP3Equal, strstr(DP3Temp,Equal));
DP3Equal[strlen(DP3Equal) -1] ='\0';
fprintf(file2, "\t%s", DP3Equal+1);
}
if(strstr(parts, MOP1)!=NULL){
strcpy(MOP1Temp, strstr(parts,MOP1));
strcpy(MOP1Equal, strstr(MOP1Temp,Equal));
MOP1Equal[strlen(MOP1Equal) -1] ='\0';
fprintf(file2, "\t%s", MOP1Equal+1);
}
if(strstr(parts, MOP2)!=NULL){
strcpy(MOP2Temp, strstr(parts,MOP2));
strcpy(MOP2Equal, strstr(MOP2Temp,Equal));
fprintf(file2, "\t%s", MOP2Equal+1);
}
}
fclose(file1);
fclose(file2);
return 0;
}