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Use when a for-loop's update expression uses the comma operator to embed I/O or computation with side effects (e.g., printf with a conditional argument), mixing loop control with branching logic
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| name | avoid-side-effects-in-for-update |
| description | Use when a for-loop's update expression uses the comma operator to embed I/O or computation with side effects (e.g., printf with a conditional argument), mixing loop control with branching logic |
A KLEE-coverage code transformation. Applying it rewrites C source so symbolic execution explores more of the program's behavior.
When a for-loop's update expression uses the comma operator to embed I/O or computation with side effects (e.g., printf with a conditional argument), mixing loop control with branching logic
Move side-effecting calls and conditional expressions out of the for-update clause into the loop body, and use locally-scoped loop variables with standard initialization/increment forms
KLEE forks on the conditional inside printf; when this conditional is buried in the loop's update expression, path constraints accumulate awkwardly with loop iteration state, and symbolic indices may be harder to concretize. Placing the branch in the loop body yields cleaner per-iteration path conditions and improves constraint solver efficiency and coverage replay
Before:
#include<stdio.h>
int main(){
int H,W,h,w,i=1,j;
scanf("%d%d%d%d",&H,&W,&h,&w);
if(H%h||W%w){
puts("Yes");
for(;i<=H;++i,puts("")) for(j=0;j<W;++j,printf("%d ",(i%h||j%w)?1000:-1000*(h*w-1)-1));
}else puts("No");
return 0;
}
After:
#include<stdio.h>
int main(){int H,W,h,w;scanf("%d%d%d%d",&H,&W,&h,&w);if(H%h||W%w){puts("Yes");for(int i=1;i<=H;++i,puts("")) for(int j=1;j<=W;++j)printf("%d ",(i%h||j%w)?1000:-1000*(h*w-1)-1);}else puts("No");return 0;}
a4341e88Use when printf statements output strings without trailing newlines
Use when array is accessed with direct user input as index (0-based indexing)
Use when the program accesses a precomputed table using an offset (e.g., arr[n-1]) that introduces an arithmetic operation between the symbolic input and the index
Use when loop variables iterate over character values (e.g., ASCII codes) to represent different operations or choices
Use when code uses a loop to search for an input value in an array and then uses the found index for further computation
Use when code reads a fixed number of characters into an array and only accesses individual elements