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char string[]="DGS021J0W0S1000.0S20000S3000.0S4000.0S50.00S60.00F";
how to get S[1-5]
thanks!
Use strncpy() standard function
char S[6] = {0};
strncpy(S, string+1 , 5);
If you want to copy from the beginning of the string to the 5th charachter, then your question should be
how to get S[0-4]
and not S[1-5] because array index in C start from 0 and not from 1. and the solution for this case will be
char S[6] = {0};
strncpy(S, string , 5);
I think you are looking for substring methods.
You can do it in two for loops in C.
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I know strings end with '/0' in C. While I'm dynamically allocating memory for a string, how do I handle that?
Also, how would you print out a dynamically allocated string? Because I've tried the regular way to print out a string and it did not work.
For the first question, I tried:
int len;
scanf("%d", &len);
char* str = (char*)malloc(sizeof(char)*len);
for (int i = 0; i<len; ++i){
scanf("%c", (str+i));
}
For the second question, I tried
printf("%s", *str);
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I have some materials showing this code. what does code means by making these assignments?
char inputfilename[128];
inputfilename[0] = 0;
char *argv[128];
*argv[1] = 0;
In C, character arrays are terminated by a null character (value 0). In both cases in your example, the code initializes the strings to "empty" (with a terminator in the first element). This would prove useful in any subsequent string operations (strcat, strcpy, etc.).
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the question is the following: "How do I split a string into 3 parts in C?"
The string is something similar to the following: "Roberta$$$Anna$$$$$$Massimo$$$"
I need to split it exactly after 10 characters (Roberta$$$, Anna$$$$$$, Massimo$$$), and please notice that they aren't separated by a spacebar, so I think I cannot use the strtok function or the library string.h to split them.
char source[] = "Roberta$$$Anna$$$$$$Massimo$$$";
char part1[11];
char part2[11];
char part3[11];
memmove(part1, &source[ 0], 10);
part1[10] = '\0';
memmove(part2, &source[10], 10);
part2[10] = '\0';
memmove(part3, &source[20], 10);
part3[10] = '\0';
You could use strncpy() or memcpy() instead of memmove().
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I'm trying to make a program to find and replace some text in a string at the moment I'm trying to change "hello how are you" to "hello bow are you" as a test.
So firstly I find the "how" by using char *substring = strstr(mystring, newstr);
which returns a pointer to "(this position)how are you" now I have no idea how to change the next 3 letters. I can strlen(newstr) for the length of the string I'm replacing "how" with but I can't find a way to change mystring starting from the pointer newstr.
Change the first character by subscripting the substring.
substring[0] = 'b';
If you want to replace multiple characters, try a loop, or use memcpy. Don't use strcpy: you don't want the NUL terminator to be copied.
memcpy(substring, "how", 3);
*substring = 'b'; as posted by user EOF my solution was as so
for (int x = 0; x < strlen(newstring); x++){
*substring++ = newstring[x];
}
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For example if:
z = "xxxx; yyyy";
How can I get the substrings so that
x = "xxxx"
and
y = "yyyy"
where "xxxx" and "yyyy" can be any string of any length?
You don't get much of built-in strings in C, let alone substrings. When you need a substring, you build it yourself by copying relevant portions of the string into a properly allocated memory buffer, and then you null-terminate the result.
Here is an example:
char *c = "xxxx; yyyy";
char x[5], y[5];
memcpy(x, &c[0], 4);
x[4] = '\0';
memcpy(y, &c[6], 4);
y[4] = '\0';
Demo.