Check for existence of token in strtok
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 |
0
active
oldest
votes
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53423201%2fcheck-for-existence-of-token-in-strtok%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
0
active
oldest
votes
0
active
oldest
votes
active
oldest
votes
active
oldest
votes
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53423201%2fcheck-for-existence-of-token-in-strtok%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
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