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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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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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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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What will happen if I use comparison operators to compare strings instead of strcmp in C? Will it compare its ASCII value and return results?
It will compare the addresses of the two pointers.
so:
char* a = "hello";
char* b = "test";
char* c = "hello";
char* d = a;
a == d; // true
a == b; // false
a == c; // true or false, depending on the compiler's behavior.
The third example will be true if the compiler decides to recycle the actual string data for "hello", but it has no obligation to do so.
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an interview question on glassdoor is as follows. With my knowledge, it is hard to deduce anything out of it. What could be an appropriate question?
A macro that computes a size_t number. Putting in a loop, it casts -1
to a size_t number, making the loop impossible to start.
as suggested by Michael Aaron Safyan, following might be the case
operates in the reverse:
for (size_t i = 0; i > ((size_t) -1); i--) {}
For explanation see the answer
The issue is that size_t is unsigned, so casting -1 to it will produce the maximum-valued size_t. One would fix this case by using a signed type (such as int or ssize_t).
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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.