pointers

[Solved] File Handling Operations in c

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The array is better declared and allocated like this: char **lineArray;. lineArray = (char **)malloc(sizeof(char *) * (lineCount-1)); strtok take a string as second argument. Replace const char j=’ ‘; by const char *j=” “; Get rid of the first strtok: lineArray[p]=malloc(strlen(line));//1st bunch of memory allocated strcpy(lineArray[p],line); printf(“%s\n”,lineArray[p]); //token = strtok(lineArray[p],j); //printf(“%s\n”,token); //serialno[p]=atoi(token); //printf(“%d\n”,serialno[p]); x=1; … Read more

[Solved] C Pointers to scan memory

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That is not how modern operating systems work. You cannot simply read out the systems ram, because applications memory is virtualized and also the OS prohibits direct access due to security policies. The OS may offer some API to access other processes memory (assumed you have the rights to do). On Win32Api this is ReadProcessMemory. … Read more

[Solved] Unexpected behavior from launching a method call on a loop variable as a goroutine

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Problem Your first version has a synchronisation bug, which manifests itself as a data race: $ go run -race main.go 0 (PrintAddr): 0xc0000b4018 0 (PrintAddr): 0xc0000c2120 ================== WARNING: DATA RACE Write at 0x00c0000b4018 by main goroutine: main.main() redacted/main.go:29 +0x1e5 Previous read at 0x00c0000b4018 by goroutine 7: main.(*User).PrintAddr() redacted/main.go:19 +0x44 Goroutine 7 (finished) created at: main.main() … Read more

[Solved] Receive from non-chan type *bool

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Those two lines in your main function shadow your global variable declaration: optQuit := getopt.BoolLong(“quit”, 0, “Help”) optRun := getopt.BoolLong(“run”, ‘r’, “Help”) If you only use them, to get a nice usage, why not create a usage function yourself? If you insist on using getopt just to create a usage, do _ = getopt.BoolLong(“quit”, 0, … Read more

[Solved] Replacing a character in a c string

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This code compiles cleanly using GCC 4.8.2 on Mac OS X 10.9.1 Mavericks with the command line: gcc -O3 -g -std=c11 -Wall -Wextra -Wmissing-prototypes -Wstrict-prototypes \ -Wold-style-definition -Werror bits.c -o bits Source: #include <math.h> #include <stdio.h> #include <string.h> extern int twosComplement(int number); int twosComplement(int number) { printf(“searching for twos complement of %d\n”, number); int temp … Read more

[Solved] Memory at runtime

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I’d suggest counting the number of lines first. int tmp; int linecount = 0; FILE *fp = fopen(“file.txt”,”r”); while ((tmp=fgetc(fp))!=EOF) { if (tmp==’\n’) ++linecount; } rewind(fp); // resets the stream to beginning of file From there, you can malloc the appropriate amount of array pointers (instead of initializing a fixed number). char** lines; lines = … Read more

[Solved] What motivates the concept of “pointers” in C, when the concept of numbers only would suffice?

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TL;DR It is completely possible to have a language without pointers. Actually, it is possible to write a C program where you store addresses in regular integer variables and then cast them to pointers. Calling pointers, and also the general concept of types, syntactic sugar is to stretch it a bit, but it’s not completely … Read more

[Solved] I need help trying to understand this piece of code about structures and pointers [closed]

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p is a pointer to a structure – this means that p ‘holds’ the starting address for a structure in memory — Hence: p = d.elmts+i represents the starting address in memory, for the current structure (i represents the address offset). In this example memory has been allocated for ‘dictSize’ structures (i.e. the number of … Read more