Check for existence of token in strtok
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I need to modify some C code that currently reads two columns of data from an ascii file, so that it can check to see if a third column is provided and if a third column is found, will read the third column.
The relevant snippet of code is currently:
struct forestListElement * forestList = malloc(nTrees*sizeof(struct forestListElement));
// skip first line
fgets(line,800,file);
cnt = 0;
while( fgets(line,sizeof(line),file) !=NULL) {
pch = strtok(line," ");
forestList[cnt].treeRootId =atoll(pch);
pch = strtok(NULL," ");
forestList[cnt].forestId = atoll(pch);
cnt++;
}
This snippet is looping over a file that currently has two columns of data (two IDs in long format). But I would like to modify the code so that after reading the first two columns it checks to see if a third column exists and, if it does, read a weight from that column. If the third column does not exist, set the weight to 1. I would like to modify the code to something like:
struct forestListElement * forestList = malloc(nTrees*sizeof(struct forestListElement));
// skip first line
fgets(line,800,file);
cnt = 0;
while( fgets(line,sizeof(line),file) !=NULL) {
pch = strtok(line," ");
forestList[cnt].treeRootId =atoll(pch);
pch = strtok(NULL," ");
forestList[cnt].forestId = atoll(pch);
forestList[cnt].forestWeight = 1.0;
if(<check if third column exists>){ \ <-- what do I put here?
pch = strtok(NULL," ");
forestList[cnt].forestWeight = atof(pch);
}
cnt++;
}
What do I need to include in the if-statement?
Apologies if this is a simple task, but I am not familiar with C and am struggling to know what to search for on Google!
Thanks.
c io token strtok
asked Nov 22 '18 at 2:50
aimaim
190318
add a comment |
I need to modify some C code that currently reads two columns of data from an ascii file, so that it can check to see if a third column is provided and if a third column is found, will read the third column.
The relevant snippet of code is currently:
struct forestListElement * forestList = malloc(nTrees*sizeof(struct forestListElement));
// skip first line
fgets(line,800,file);
cnt = 0;
while( fgets(line,sizeof(line),file) !=NULL) {
pch = strtok(line," ");
forestList[cnt].treeRootId =atoll(pch);
pch = strtok(NULL," ");
forestList[cnt].forestId = atoll(pch);
cnt++;
}
This snippet is looping over a file that currently has two columns of data (two IDs in long format). But I would like to modify the code so that after reading the first two columns it checks to see if a third column exists and, if it does, read a weight from that column. If the third column does not exist, set the weight to 1. I would like to modify the code to something like:
struct forestListElement * forestList = malloc(nTrees*sizeof(struct forestListElement));
// skip first line
fgets(line,800,file);
cnt = 0;
while( fgets(line,sizeof(line),file) !=NULL) {
pch = strtok(line," ");
forestList[cnt].treeRootId =atoll(pch);
pch = strtok(NULL," ");
forestList[cnt].forestId = atoll(pch);
forestList[cnt].forestWeight = 1.0;
if(<check if third column exists>){ \ <-- what do I put here?
pch = strtok(NULL," ");
forestList[cnt].forestWeight = atof(pch);
}
cnt++;
}
What do I need to include in the if-statement?
Apologies if this is a simple task, but I am not familiar with C and am struggling to know what to search for on Google!
Thanks.
c io token strtok
asked Nov 22 '18 at 2:50
aimaim
190318
1
Did you read the documentation forstrtok? What does it return? And what does it return if the next token isn't found?
– Ken White
Nov 22 '18 at 4:13
add a comment |
I need to modify some C code that currently reads two columns of data from an ascii file, so that it can check to see if a third column is provided and if a third column is found, will read the third column.
The relevant snippet of code is currently:
struct forestListElement * forestList = malloc(nTrees*sizeof(struct forestListElement));
// skip first line
fgets(line,800,file);
cnt = 0;
while( fgets(line,sizeof(line),file) !=NULL) {
pch = strtok(line," ");
forestList[cnt].treeRootId =atoll(pch);
pch = strtok(NULL," ");
forestList[cnt].forestId = atoll(pch);
cnt++;
}
This snippet is looping over a file that currently has two columns of data (two IDs in long format). But I would like to modify the code so that after reading the first two columns it checks to see if a third column exists and, if it does, read a weight from that column. If the third column does not exist, set the weight to 1. I would like to modify the code to something like:
struct forestListElement * forestList = malloc(nTrees*sizeof(struct forestListElement));
// skip first line
fgets(line,800,file);
cnt = 0;
while( fgets(line,sizeof(line),file) !=NULL) {
pch = strtok(line," ");
forestList[cnt].treeRootId =atoll(pch);
pch = strtok(NULL," ");
forestList[cnt].forestId = atoll(pch);
forestList[cnt].forestWeight = 1.0;
if(<check if third column exists>){ \ <-- what do I put here?
pch = strtok(NULL," ");
forestList[cnt].forestWeight = atof(pch);
}
cnt++;
}
What do I need to include in the if-statement?
Apologies if this is a simple task, but I am not familiar with C and am struggling to know what to search for on Google!
Thanks.
c io token strtok
asked Nov 22 '18 at 2:50
aimaim
190318
I need to modify some C code that currently reads two columns of data from an ascii file, so that it can check to see if a third column is provided and if a third column is found, will read the third column.
The relevant snippet of code is currently:
struct forestListElement * forestList = malloc(nTrees*sizeof(struct forestListElement));
// skip first line
fgets(line,800,file);
cnt = 0;
while( fgets(line,sizeof(line),file) !=NULL) {
pch = strtok(line," ");
forestList[cnt].treeRootId =atoll(pch);
pch = strtok(NULL," ");
forestList[cnt].forestId = atoll(pch);
cnt++;
}
This snippet is looping over a file that currently has two columns of data (two IDs in long format). But I would like to modify the code so that after reading the first two columns it checks to see if a third column exists and, if it does, read a weight from that column. If the third column does not exist, set the weight to 1. I would like to modify the code to something like:
struct forestListElement * forestList = malloc(nTrees*sizeof(struct forestListElement));
// skip first line
fgets(line,800,file);
cnt = 0;
while( fgets(line,sizeof(line),file) !=NULL) {
pch = strtok(line," ");
forestList[cnt].treeRootId =atoll(pch);
pch = strtok(NULL," ");
forestList[cnt].forestId = atoll(pch);
forestList[cnt].forestWeight = 1.0;
if(<check if third column exists>){ \ <-- what do I put here?
pch = strtok(NULL," ");
forestList[cnt].forestWeight = atof(pch);
}
cnt++;
}
What do I need to include in the if-statement?
Apologies if this is a simple task, but I am not familiar with C and am struggling to know what to search for on Google!
Thanks.
c io token strtok
c io token strtok
asked Nov 22 '18 at 2:50
aimaim
190318
asked Nov 22 '18 at 2:50
aimaim
190318
asked Nov 22 '18 at 2:50
aimaim
190318
asked Nov 22 '18 at 2:50
aimaim
190318
asked Nov 22 '18 at 2:50
aimaim
190318
190318
1
Did you read the documentation forstrtok? What does it return? And what does it return if the next token isn't found?
– Ken White
Nov 22 '18 at 4:13
add a comment |
1
Did you read the documentation forstrtok? What does it return? And what does it return if the next token isn't found?
– Ken White
Nov 22 '18 at 4:13
1
1
Did you read the documentation for
strtok? What does it return? And what does it return if the next token isn't found?– Ken White
Nov 22 '18 at 4:13
Did you read the documentation for
strtok? What does it return? And what does it return if the next token isn't found?– Ken White
Nov 22 '18 at 4:13
add a comment |
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1
Did you read the documentation for
strtok? What does it return? And what does it return if the next token isn't found?– Ken White
Nov 22 '18 at 4:13